PA28Viking:
No, no mistake at all. I'm rather stunned that you would think that Ryanair would not understand your difficulties and simply waive the painful cost of having a customer with a credit card.
When, in two months time, Ryanair introduces their "fresh air" flights, decompress the cabins and start charging £50 for the oxygen mask to drop you will be one of those saying "Wait...shouldn't air be included?"..well, until you turn blue...and please have the exact currency for Cabin Crews convenience.
"Thank you for flying Ryanair. Cheap flights until you pay".