TSR2
I wouldn't entirely agree with you on that, other wise the FR's of the retail world would be up to no good. The bottom line is that the price advertised for a product or service is the price you should pay, obviously from time to time shops make errors, but even then most will honour the displayed price.
It is more difficult when you come to WEB based transactions, because the yield management systems will often increase prices if demand increases and this can happen during the time it takes to go through the various steps involved, i doubt that FR are sat there waiting to poke your eyes out because you are trying to book a short notice flight from DUB/EDI, most web site will state that the booking is not confirmed until you receive a booking confirmation, however what will not happen is the price increasing between the statement CONFIRM PAYMENT and confirmation, the banks will not allow that to happen because the point it which you press submit CONFIRM PAYMENT is the point of contract.
This is different to the retail situation above, where to have a displayed price and change it at the till other than gross error would be in breach of various reg, take the case of driving into a petrol station that is showing fuel 129p litre filling your tank (the point of delivery in contract terms) and being asked for 136p at the till, you could offer to pay 129p and if they refused, leave them your contact details (having taken a note of the display price, photo even better) and drive off.
FR are in general cheaper than other airline most of the time, but often not much less, their website try to stay within or on the edge of the rules and reg, just. But they are cheaper because they have the lowest cost per seat in Europe by a long way ( we all know how and why) its a very clever business model whether you like them or not, a friend came back from a week in Lanzagrotty having flown both ways with FR (3 adult 2 kids) and hated it, his wife got abused by gate staff for having bought somethging in the terminal extra bag and they had to repack between the three adults on the way out because 1 bag was 1kg over the other 2 & 3 kg under. He'd flown with them before, i told him to read rules to the letter, i asked him why having known and flown before he went with them again? the answer, yep they were £120 cheaper and that was the weeks beer money!!
FR are safe, punctual & obnoxious, but cheap, if they ever lose that edge there done for.