By Bob Howard
BBC Radio 4's Money Box
The leisure group collapsed leaving customers out-of-pocket
More than half of the 60,000 XL customers who have sought refunds are still waiting for their money six months after the firm's collapse.
The issue has been complicated by a dispute between Atol and the banks over who should pay some of the claims.
Atol wants credit card providers to refund anyone who paid for all or part of the holiday with their cards.
But some banks are telling these customers to seek refunds from Atol instead.
Many XL customers thought they had two types of protection when the travel group collapsed in September.
Firstly, the Civil Aviation Authority's Atol compensation scheme, which most travel agents are signed up to.
Secondly, if they paid by credit card, they believed their credit card company would be liable under Section 75 of the Consumer Credit Act.
XL customer Shirley from Suffolk booked a holiday to Florida for her extended family costing £6,000.
She paid the deposit on her Tesco credit card and other members of the family paid the balance.
She had first applied to Atol to get her money back but three months later Atol told her to go to Tesco to get her full refund.
Then, after a further three month wait, Tesco Personal Finance wrote to say it was not refunding her and advised her to seek her money back from Atol.
Shirley told BBC Radio 4's Money Box programme she was frustrated: "I think whatever way you pay for a holiday, you should be able to get your money back. It seems like nobody wants to take responsibility."
Atol wanted Shirley to claim under Section 75 of the Consumer Credit Act, which holds credit card companies liable for goods or services which are not received, even if just the deposit was paid for this way.
The payment card industry says it reached an agreement with Atol several years ago over who should pay out in these situations.
The umbrella body - the UK Cards Association - has written to its members to remind them of their obligations.
The organisation's Sandra Quinn admits some customers do not know which way to turn: "I think there has been quite a lot of to-ing and fro-ing between Atol and the credit card companies.
The Financial Ombudsman Service may well have a role in this
Those people who've paid by credit card have a legal right to claim from their credit card company."
The Civil Aviation Authority (CAA) says it has paid out £20m to more than 20,000 claimants. It said it was hoping to settle claims by September.
The CAA's David Clover admitted where there is a dispute with a card company over who pays out, some customers may have to resort to the Financial Ombudsman Service in order to obtain their refund.
"We are seeing some claimants coming back to us having gone to their credit card companies. We will review all these cases. The Financial Ombudsman Service may well have a role in this as well," he said.
BBC Radio 4's Money Box was broadcast on Saturday 11 April at 1204 BST.
The programme was repeated on Sunday 12 April at 2102 BST.