An investigation by MoneySavingExpert (MSE) found that some holidaymakers who had booked trips with the budget airline were later told they could only fly if they gave back their 'Chargeback' refunds.
In one case, the customer was given just a few days notice before their planned trip.
The website says that ‘we've spoken to three passengers who were told they could not fly until they returned the money’.
The amounts customers have been asked to pay back range from £400 to £630.
MSE reports that Coby Benson from Bott and Co and Colin Murphy from Leigh Day said the airline was wrong to then ban passengers from flying unless they paid the money back.
Mr Benson told the website: ‘The question is whether or not there were 'reasonable grounds' to deny the boarding, and in this case I don't think there are.’
Have you got a flight booked with Ryanair and are worried about this? Let us know.