I think it's not so much that the amount is too big, but that these experiences leave such a horribly bitter taste in the mouth. Made worse too by the fact that many customers don't really want to take the 'I'll never fly them again' solution, because that may prove to be cutting off one's nose to spite one's face. So there's the knowledge that you are likely to want to give this company more of your money in the future, but absolutely don't want to give them another penny until they settle their debt to you.

I certainly sympathise with OP here.