Some passengers have now been waiting days to return home
Some UK banks are waiving fees for money withdrawn by passengers stranded overseas by the volcanic ash cloud.
But those in need of an extension to their credit card limit to pay for a way home must have the increase approved by their card issuer.
Many travellers have reported that they have paid large amounts for alternative travel plans.
Those facing financial difficulty are being urged to contact their bank or credit card provider.
The phone number is generally found on the back of the debit or credit card.
Some passengers have reportedly spent thousands of pounds in their attempts to get back, with others facing additional hotel and food costs.
The British Bankers' Association, which represents banks, said that financial institutions understood that many people were incurring costs and expenses that they had not budgeted for.
"Banks are putting arrangements in place to help their customers and, in most cases, will deal with requests for additional finance or claims for charges to be waived on an individual case-by-case basis," a spokesman said.
"Anyone who is concerned should contact their bank."
However, the Lending Code - the list of rules which should be adhered to by the banks - has no specific requirement for exceptional circumstances.
Rob Skinner, chief executive of the Lending Standards Board, said he would expect credit providers to deal with cases sympathetically.
Consumers should speak to their credit provider about getting an extended credit limit and discuss the repayment terms at the same time - such as how long they have to pay the money back.
The provider must still judge people's ability to repay before extending any credit offers.
Specific banks have slightly different policies over what assistance they will provide.
RBS/NatWest customers should get refunds on any fees for cash withdrawals from cash machines overseas if they are affected by the ash cloud. The bank said it would extend credit limits "where appropriate".
HSBC UK customers went further later by offering refunds of fees - but not commission - to anyone using their debit or credit cards at overseas ATMs.
"This is a blanket refund and will apply to customers whether they have been affected by travel related problems or not. The refund applies to all ATM transactions since Thursday last week," a spokesman said.
Lloyds TSB said it was contacting personal banking customers by text message to explain the support that was available.
It has reversed an initial decision not to refund cash machine fees, and said it would also waive charges incurred by the disruption, such as charges for late payment or customers inadvertently going over their credit limit while abroad - but customers should get in touch as soon as possible.
"We know this is a difficult and potentially expensive time for many of our customers who are currently stranded overseas," said Helen Weir, of Lloyds Banking Group.
Barclays and Barclaycard said they would consider requests for overdraft or credit limit extensions.
All affected travellers should request a refund of any fee imposed because they have gone above their overdraft limit.
There are also providers of money transfer services, which allow relatives to transfer money to their stranded family. However, there is a charge for these services.