how annoying!
I think the quote part is really interesting and although I'm not a lawyer these are my thoughts:
1. if it had taken them longer to fit than expected, would they have done the extra hours FOC? I doubt it?
2. is there a T&C on the back on any paperwork to say if it's a quote or estimate?
Looking at CAB
http://www.adviceguide.org.uk/nireland/ ... imates.htm
they seem to say a quote is binding and an estimate it flexible but one could argue you were buying "his time" and so the "time" element wasn't delivered.
Anyway to summarise:
1. If it's a quote probably have to stick with it, if an estimate you can probably negotiate
2. "Reasonable" travel time would normally be built into the quote unless they clearly separate the cost in their T&C's. If they have a higher rate for London then that would probably mean that "reasonable" travel to London is already taken into account and so they'd have to show that they'd travelled much further/took more time than "reasonable"
3. I'd Google the firms name and see if anyone else has complained? It might be sharp practice!
4. Lastly, you could offer to pay a fair amount in full and final settlement but be prepared for them to a) try to sue you or b) never use them again!
hope that helps!