Although more difficult in the age of computer controlled everything, I have found it is always preferable to to do your research before consulting the motor trade. Simple stuff like checking front brake pads occaisionally can save a set of discs or stop a rip off during a tyre change. A little knowledge can be dangerous but knowledge is also powerful when dealing with the motor trade, but this also applies to any other outfit providing a service. If you have a problem with a bit of kit, having had a look at an exploded diagram and repair procedures online can help tremendously when discussing its repair. For example a Jazz clutch slave cylinder replacement is a quick easy job, Ford Fiesta is a gearbox out job.