In March to July, many brands' customer communications collapsed under the pressure of the national coronavirus lockdown.
One in five shoppers (22%) were unable to contact retailers and service providers to resolve their complaints, according to our July survey of 1,221 Which? members.
We heard stories of phone calls unanswered, emails ignored and weeks-long waits for resolutions.
Here, we look at the problems people faced, and what you can do to make your voice heard.
The government's instruction to work from home in March shook up the way many businesses were running. Coupled with that, the lockdown created complications and difficulties for retailers, that suddenly had to change how they operated.
In many cases, this led to customer service shake-ups that were less than helpful.
Some brands shut down phone lines, while others greeted callers with long automated messages that warned of the delays customers might receive while also marginally lengthening them.
Even this month, 13% members of the general public said they had difficulty getting through in the previous firve days to customer services departments of shops or service providers to ask questions, based on our survey of 2,000 members of the general public taken between 16 and 20 October.
Which? members shared experiences of high street brands ignoring them after failing to deliver orders. Others were unable to return faulty products, and some said they only managed to get solutions when they could once again visit stores.
Jim Glover encountered difficulty fitting an Ikea kitchen just after lockdown started.
'We fitted our Ikea kitchen at the worst possible time during the lockdown,' he told Which?, 'and we had great difficulty contacting the company to arrange delivery and to get answers.'
Jim was unable to get through to Ikea over the phone, so he tried getting in touch via email. Eventually he was successful, but it took a long time.
'We are happy with the kitchen and we eventually got answers relayed through Ikea's design team, but we could get no response to direct phone calls and emails for several months,' he said.
When Which? contacted Ikea, it apologised for the inconvenience its customers had faced during the lockdown.
A spokesperson said: 'COVID has forced all of us - as customers and businesses - to adapt and adjust in extraordinary circumstances, and we thank customers for their patience. We are pleased to hear that Mr Glover is happy with his kitchen.'
Ikea also provided an explanation for how this happened:
'As we went into lockdown, we closed our stores and temporarily suspended some services to customers in order to adhere to government guidelines, including our kitchen installation and measuring services.'
Ikea says it suspended its customer services phone line temporarily, as the home working transition meant only a limited team was available. It's now open, and Ikea says it's working on new ways to increase call capacity and help customers with problems.
One member had to take a retailer to court to get a refund, because of a total lack of communication.
Graham Ettridge struggled to find additive-free Rocks orange squash at the supermarket, so he turned to online health goods retailer SuperfoodUK, but his order never arrived and he couldn't reach SuperfoodUK by phone or email.
'It was only when I finally had the claim issued by the court that two days later the company refunded the value of the item,' he told us.
'The value of the goods was only £21.50,' he said. 'But I was so fed up with people being ripped off.'
SuperfoodUK told Which? that Graham's experience was a 'one-off' caused by external supply chain factors - such as 'inconsistent deliveries from suppliers, couriers running over capacity and staffing issues' - and that systems are now in place to ensure it doesn't happen again.
Dealing with complaints and queries properly and efficiently saves customers a lot of time and worry at what is already a very stressful period for many.
Businesses need to be better prepared to provide customer service this winter, as we all pull together to comply with the restrictions.
Complaining about a product or service might not be something you're used to, but sometimes it's something you need to do.
To help you make your voice heard, our expert guides walk you through the process step by step.