Normally it'd be a case of you coming in and us asking 'what's wrong'. If you say 'gears are skipping' And we would tell you to come back in X amount of time plus we'd give you a quote. We'd completely check over the shifting system and if its a simple fix we'd call and tell you you could pick it up. If it was gonna cost more to fix than quoted, we'd call you before doing anything. Rule #1 is you can never charge more than quoted on a job unless contact has been made and price accepted.