Why are most garages rip off thieves?

I moved to darwen 3 weeks ago, 2 weeks ago the flywheel broke on my van, took it straight to a garage called anchor garage in darwen and the pricks done me over for starter motor clutch lower arm and a flywheel, I'm ready to rip the guys face off, I'm gonna try trading standards, I've had a quote from another garage for all that work and he said 500 quid max. Do not use anchor garage in darwen whatever you do he's a rip off merchant!