most professions that bill by the hour work this way? squeaky brakes isn't a plausible example, but this isn't uncommon for electrical issues in luxury cars. the mechanic spends days/weeks chasing it down and eventually asks you if you want to keep paying them to look. if you say no, you still have to pay for the time they already spent. if you say yes, there's no guarantee they eventually fix it. or they come up with a root cause and give an estimate to fix. you still pay if they're "obviously wrong".