I'm no authority on legal matters but, if they are having communication trouble with each other, i suppose it woiuld be the top bosses job to sort it out, and the only way they're gonna do that, is with a nice persuasive kick up the arse. Don't see why u should pay for other peoples incompetance, so the least they should do is fork out for the hall sender and if you're feeling brave, ask them to sort out the rear caliper as it was their job to do it in the first place. Did u get written quotation from them? Always get these things written down so theres no comebacks. Hope you get it sorted m8,