I think they could have atleast told him the tach wasnt working properly and ask if he still wanted it installed completely...and if he said no, they could have charged half. Ricky and Joey did my civic, i was there first customer in the new shop and they do good work.....My civic ran good........only problem i had was when ricky test drove the car, it blew out the exhaust gasket but he told me to bring it and he would replace it but i was lazy. But sorry to hear your mishap........im sure they would have corrected things if you would have went to them.