Thanks Tony,
Yes £180-£200 is what I expected to pay. You're also right about screw length or lack of; needs longer bolts for sure... Don't want to fork out for new boiler though-apart from aforementioned possible of mounting everything else seems to be fine-they're not cheap things are...
Useless21 did you get yr boiler fixed? If you did, how much did you pay?
I have the same issue, i've recently just moved into a new house and had to have a plumber out for a different problem. He had a quick look at my boiler and pointed out that the top right bolt was coming out of the wall...