You do not. Several questions arise here. One is integrity. Another is the ability. Another reason is trust.
If you expect your vehicle to a dealer of new vehicles, a garage, a gas station, tire store, auto service shop specialized branch or any other type of service centers to be treated honestly and fairly. You do not want to, which exploits are being lied to unfair advantage, says you need parts or services you do not really need for parts that were not replaced, or services that have not been charged, or deceived in any way feel conveys, as it were, is not it?
If you take your vehicle for routine maintenance like oil changes, tune-up, tire rotation, etc., you should be told what items are repaired or replaced, how much parts and labor cost and how long it will take. You should then complete the work, as will be described in a reasonable time to wait at this price.
If you take your car because you obviously do with some kind of problem with her or because she needs to operate, make an accurate diagnosis of the problem, a complete description of what the parts and / or services will be replaced granted to the problem, a fairly accurate estimate of what repairs will cost, and an estimate of how long it takes to fix. No work is to begin before they are allowed (preferably in writing) and no additional compensation should be done if you allowed to work after someone explains why the extra work with an estimate of costs. A shop should also be ready to show you the old parts they removed from the vehicle and bring them to you if you (unless replacing a deposit for parts that may be necessary in some cases required) . wish » Read more: How do I know I’m not getting ripped off when I take my car in for service or repairs?
If you think you have cheated, first try to solve the problem with the service manager. If you are accused of knowing something you did not request, authorize, or to understand, try to get an explanation. Maybe it was just a misunderstanding.