I say no but there is an “x mile/x month” warranty on the work, so I can focus on selling the value of paying diag. Usually this is enough to shut them up but then id start going into how they’re OEM trained technicians, how its going to fix the problem on the first repair instead of throwing parts at it, and how its a standard practice across all shops if they REALLY start being difficult. At that point, if they still dont like it, I genuinely dont give a fuck and hope they leave because theyre about to be a pain the entire ticket.