A & A Japanese Car Specialists

My car failed on smog so I drive around to find a car repair shop and I saw this placed is open and iwent to them and ask if they can fix mr car cause failed on smog and engine light is on. they told me its cost me $40 for diagnose and if they fix it they waive the diagnose fee. then they call me after two hours they said is a computer wire problem and it will cost me $560.00 dollars then isaid go ahead but after 15 minutes icall back isaid dont fix it yet cause I would like to get a second opinion they said its already tore a part. and iaks for the old wire harness part they said they dont have it and it said is a smaal parts of harness only and a lot of work to fix it. and on the reciept is no parts # and explanation what exactly they do ,only repair the electrical wrie, I know icannot get my money back but I felt being riff off.on the job they do to fix my car.what should I do !!!