I agree bro, if person is non technical then these showroom guys looted anyone. one have to be technical to trace the problem and try to resolve it. this forum is so helpful to understand how to resolve the issue without spending money and then you can Search the market to resolve the issue.
Once I visited a shop because of mouth of words, he used to do tuning and everything, he can not make me fool because i know what is everything but kids bringing him there japnese cars paying them 15k for just cleaning plugs , thoratel and Cat which i can get it done in 2500 rs.