Originally Posted by S1rst

It amazes me how some people are prepared to gain an enemy over a few quid.

At the end of the day if he's not willing to stick to what you agreed then he should be willing to accept what ever might happen as a result. Id offer to pay for the fine as a gesture of good will (£30 fixed penelty at guess?), and then see what he says. If he still doesnt want to play ball, then decide what to do next.