The extraordinary exchanges came after Dublin-based web designer Jason Roe posted on his site:

"As I was booking flights to Cork, I noticed something a bit strange. When I went to change my flight times, all of the prices on the flights had changed to ?Total Cost of Flight 0.00?.

Roe said he worked out what had happened - in trying to avoid credit card charges, he jumped into the Ryanair voucher section - in which there are no charges on vouchers. "So it can be a good way to avoid charges," he added.

Get the full story at Times Online