Yeah, I worked it out that it was over £500, perhaps I should have been firmer in making him pay but I did email him several times. I just dropped it for an easy life and I had the bigger goal in mind for splitting the house money.
I hate confrontation though, in any situation. But if he was a 'normal' person, I would have no qualms. It is because it is him, and I think he probably knows that.
