I wonder if we all tendered a tenner after ordering and then due to their no change policy said oh well I am afraid I can't accept your coffee. Perhaps this would make them sit up and think? Although I have a vague recollection that the cabin crew on 10k a year might have to foot the bill so it probably wouldn't end up hurting RYR at all unfortunately.
My policy is to never buy off them in the first place. If I have purchased a 20 quid fare then I am damn well not going to give them a quarter more for some refreshments that is for sure. I can never understand people that throw money at the airlines on a relatively short hop for horrible instant coffee and tired old sandwiches.