Refuse to pay for damage to paint

I Took my Mitsubishi Triton for its 80 00km service the Friday morning early.I went to collect my car and I noticed that there was an area, about 10cm long an 3cm wide, where they chipped the paint of my bakkie. With that they also left my car unlocked next to the side of the road and did not wash the car properly. They also charged me R140 to wash my car, which I did not agree to. When I confronted them the manager pointed out (through a photo he was shown) that because my car has been resprayed, again there is no evidence to support this, they are cleared from compensating me for any of the damages that might have occured. They also claim that it was the high pressure hose that removed the paint. In other words they charged me to leave my car unlocked, dirty and with a chip in the paint. If that is not good service I do not know what is... My lawyer suggested I get three quotes and sue them for the cheapest amount. I really wish that big companies like McCarty Kunene Witbank - Mitsubishi did not have to bully small customers like me to save a few bucks. I would strongly recommend that you, like I will, find some place else to service your Mitsubishi