That sounds awful, the specialist in Birchington seems to have misdiagnosed the heating problem and the gutters should have been done better but you say the rest of the work was fine? A lot of garages are run on a shoestring as costs can be high... long hours etc so they may not get the phone etc.. You should talk to them and voice your concerns maybe give them a second chance on something easy. How many staff have they? One bad egg etc! The second garage sound like a bunch of cowboys (maybe) Sometimes knowing someones limitations is best? But as Rick says above check first.