Lloyds, NatWest and Royal Bank of Scotland (RBS) have improved their payment protection insurance (PPI) complaints processes for checking against a claimant's full policy history following a Which? investigation, but many banks have kept barriers in place.
The worst case we encountered was with NatWest customer Valarie Henderson, 63, from County Durham, who almost missed out on £12,784 in compensation.
Valarie's bank had previously admitted to mis-selling four policies, but when she was prompted to make a final check of all accounts in 2018, she discovered that PPI had been added to 13 rollover loans.
We don't think it's fair that people making a claim are encouraged to give details such as account numbers without being warned that where they reference a specific policy, only that product will be investigated.
While some banks have made changes since our investigation, most are still putting the burden on customers to make sure all products are checked for PPI mis-selling:
We are urging claimants to check they haven't been unfairly denied compensation and to submit another claim for mis-sold PPI against all products if they've previously made a single-product claim - even if that claim was successful.
The FCA says it continues to challenge firms to reduce barriers in their PPI-checking processes, including by making it easier for consumers to ask for all brands or PPI-types to be included in a single checking enquiry.
But, online and postal PPI forms from Capital One, HSBC (and First Direct), M&S Bank and Santander don't enable you to easily ask for all products and brands to be included.
When we asked if there were plans to change their claims processes, all of these banks confirmed their original positions - assessment of mis-selling is limited to the products specified.
Capital One said: 'Customers can find out if they had PPI by using our free online checking service to identify all the accounts they held with us that had PPI. Customers can also call and request us to investigate a single specific account or multiple accounts.'
HSBC said that customers can use its online checking form first, which will mean it searches for all PPI policies ever held, negating the need for an 'All Accounts' button on the complaints form, and 'general enquiries can be raised through the Virtual Assistant, by starting a Live Chat session (found in Help and Support tab), or by ringing the helpline details as contained on the PPI landing page.'
Santander said it would include related products (such as a chain of loans) and told us it has a button at the bottom of its form if you wanted to add another complaint, so multiple policies can be on the one form. But we question whether this really makes it easy for claimants to ask for all policies to be included.
A spokesperson for Santander said: 'We take this approach to ensure that a PPI product with which a customer is satisfied is not included within an assumed but unintended complaint.
'We believe our telephony channel and written complaint teams are able to discern whether a customer wishes to make a complaint about all Santander brand and credit products, or a specific product, including where they are unaware of the account numbers for such products.'
An M&S Bank spokesperson said: 'If we receive a general enquiry to check whether someone had PPI, we will provide information on all the relevant accounts, regardless of the information that is provided.
'If we receive a PPI complaint about a specific account, then only that account is investigated. If they specify all accounts, or are unsure, then we would investigate all.'
Which? consumer rights editor, Eleanor Snow, said: 'It's disappointing that some banks are continuing to put the burden on customers. Banks should be more proactive about compensating customers who contact them about PPI to ensure they receive the full payout they are entitled to.
'With the deadline to make a PPI claim fast approaching, we would encourage anyone who thinks they might have additional policies to , even if they've had a payout on one policy already, so they can be sure they've received all the compensation they are owed.'
We think, at the very least, banks should make it easy for people making a claim to ask them to check against all brands and products at the same time.
Following our news story, NatWest and RBS told us its systems have been updated to do just that:
Lloyds customers also now have the option to 'review all' products using its online PPI complaint form though this wasn't the case last year, when we first exposed this problem.
The bank added that customers contacting them by telephone also have the opportunity to include all products in their claim.
Nationwide told us that it has always offered customers the option to search 'all PPI policies' or specific policies only, and reviews any personal loans that are in a chain regardless of the loan account number quoted.
Crucially, the building society said that it informs members of all policies held through the enquiry response provided in order to bring a complaint, and then lets them choose which ones they believe were mis-sold.
A Nationwide spokesperson said: 'Factors such as whether they have used the policy to make a successful claim, how much they paid for it or the importance of the lending to them might help them decide if they want to raise a subsequent mis-selling complaint.
Since the beginning of the year, we have helped people start 68,189 PPI claims. The average compensation payout is £2,500, but we have heard from claimants who have received more than £18,000 back after .
Don't be put off pursuing your claim if you subsequently receive a questionnaire asking for further details from your bank.
We reported in that Lloyds and Santander routinely send long, laborious forms for claimants to complete - in some cases one for each PPI product sold - potentially discouraging them from pursuing their complaint.
If you receive one from any PPI lender, fill out as much as you can remember, but don't feel obligated to complete it all. It shouldn't affect your claim if you don't fill out every section, although the banks don't always make this clear.
And don't forget that many people who have had their PPI complaint rejected should lodge a new claim for 'undisclosed high commission', even if it wasn't mis-sold because firms didn't disclose how much they earned in commission. Read more about this .
As many as 64m PPI policies were added to credit cards, store cards, mortgages and personal loans, mostly between 1990 and 2010. It was even added to some current accounts, billed as 'overdraft protection' insurance.
PPI was widely mis-sold by lenders - to people who couldn't claim on it, thought it was compulsory or weren't even aware it was added in the first place.
If you don't have any old statements or product paperwork, you can also: