Customers of Travelex who ordered money online have been left with no travel money from the company, which is in the midst of a cyberattack.
The foreign currency trader confirmed on Tuesday that it is the victim of a cyberattack.
The criminals behind the hack are demanding payment or they are threatening to delete the company's computer systems and sell customer data online.
Travelex says that there is no evidence customer data has been compromised.
In response to the cyberattack, Travelex has taken all computer systems offline, affecting thousands of sites in dozens of countries.
Cashiers have been resorting to using pen and paper to keep money moving at cash desks in airports and on high streets, and orders online have also been affected.
If you ordered money online from Travelex you may have been affected, and your travel money may not arrive before you travel.
If you can afford to wait, Travelex says it will still be fulfilling orders and refunding those affected once the situation is resolved.
If you want get a refund before Travelex is up and running again should contact the firm via social media or over the phone to try and arrange this.
If that is unsuccessful your next steps will depend on how you paid for your travel money:
You can ask your bank to use a process called chargeback. The bank will reverse the transaction, clawing your money back from the recipient account.
It applies to all debit cards, although exact rules may vary between the Visa, Maestro and American Express networks.
For all credit card transactions with a value of more than £100 and less than £30,000, Section 75 of the Consumer Credit Act means your credit card provider is jointly liable for any breach of contract.
In short, if the company you made the transaction with is unable to fulfil it, you can claim your money back from your credit card provider.
If you used a credit card but spent less than £100, you can also try using chargeback.
A Barclaycard spokesperson said: 'We understand that Travelex is still processing physical orders, so anyone who has ordered currency online should still be able to collect it at one of the Travelex bureaus.
'While we approach individual claims on a case-by-case basis, it's likely that anyone who has bought their currency using a Barclaycard will be covered under Section 75, should Travelex be unable to fulfil the order.
'We're continuing to review the incident to inform the protection customers should be afforded under Section 75.'
Whenever there is confusion, scammers often circle like sharks looking to take advantage of the situation.
We urge anyone affected to watch out for fake websites or emails that claim to be helping or asking Travelex customers to 'verify' their information. Phishing attempts by scammers to steal your personal data are a common occurrence after a major hack or data breach.
The situation is still developing and it is unclear whether personal data has been compromised by this cyberattack.
Travelex says that there is no evidence customer data has been compromised, but the hackers say otherwise.
There are a few sensible steps you can take as a precaution:
Chief Executive of Travelex Tony D'Souza, said 'Our focus is on communicating directly with our partners and customers to protect them and their information from any further compromise.
'We take very seriously our responsibility to protect the privacy and security of our partner and customers' data as well as provide an excellent service to our customers and we sincerely apologise for the inconvenience caused.
'Travelex continues to offer services to its customers on a manual basis and is continuing to provide alternative customer solutions in the interim. We are working tirelessly to bring our systems back online.'