What bits do you need to replace, do you know? If it's just the flush handle it's a piece of cake. If it's the ball cran, it's easy as well. To be honest, it is fairly simple if you are any good at DIY. If you know any plumbers then ask them to do a "homer", rather than phone up a plumber from the yellow pages. That way, 50 quid should cover it. But try it yourself first, take the broken bits out and take them down to plumb center or b&q to match the replacements.