I was sat next to a man who ordered a meal and paid with his card. They initially tried to give his meal to the wrong seat but eventually got it right.
About 10 mins later when he was half way through eating another member of cabin crew asked him for payment. He stated he had already paid and the other member of cabin crew confirmed this (after both quibbling next to my head for 5 mins). However the Cabin Crew Member who asked for payment came back to the man and said it wasn't on the system and he needed to pay it again as it hadn't gone through. He refused saying he would call his bank on landing and if he hadn't paid he would then pay but would not be paying twice.
This woman would not leave it alone. She stood over him (and me) for over 10 mins arguing the case, insisting he pay, saying he should not expect to eat for free and saying if he didn't pay they would take it out of her wages.
To be honest she was rude and unprofessional but at the same time the whole cabin crew looked stressed and unhappy and I wasn't aware the crew would be treated so badly that their wage would be deducted for a non payment.
So I think she was unreasonable but at the same time must be treated appallingly by Ryan Air to behave this way in the first place.