Kmart Tyre & Auto Service Merrylands

Very disappointed with Kmart Tyre and Auto Service Merrylands. Yesterday i gave me car for servicing and the left rear window was not working. This is the first time i checked on the prices and i still got ripped off. They put in a after market regulator and motor (as per them it was not working) and they were charging me 335 for the parts plus labor. They said that the labor was 175 for 1.5 hrs labour whereas as per they expertise it was only half an hours job.... an hour to tops. I checked online and the regulator + motor (after market) does not cost more than 80 but they were charging me 160 for it. I have been trusting them all these years and to my astonishment I caught them ripping me off yesterday. I just wonder how much they have ripped me off in the past as i have changed my battery, tyres, repaired shocks etc from them. When they called me to tell me the problem with the car and the cost, i agreed to it thinking they would not cheat and give honest quotes . But now i know you cannot trust them with part prices. They put a very large markup on the parts even if you are they ongoing customer. When i questioned them about the price they only argument was that I agreed to the price. I guess it was my mistake to trust their integrity. How low? From 1,800 they lowered the total cost to 1500. A cost difference of 300, what if I had not spoken. I just wonder the issues they tell you in your car is genuine issues or just made up. I would not recommend anyone to trust Kmart Tyre and Auto Service Merrylands with prices as it is most likely you are being ripped off if you are not aware of the prices. One of their staff member was quite rude while I was being calm being ripped off. He just threw the quote on the table and took off.