incompetent rip-off artist

First, some background. My wife twice took her car to Peters Auto Care for servicing. The first time, she noticed the morning after collecting her car that our garage floor was full of oil. It turns our Peter's "mechanics" had not put the sump plug back properly and all the oil ended up on the floor! The second time, when she got her car back there was a strange alarm when she turned on the ignition and all the dashboard lights flashed on and off. When I took it back to Peter, he had the cheek to ask me if the car wasn't "like that when we brought it in". Three visits later and the problem persisted until we had to go to an auto electrician to sort it out. Turns out Peter's "mechanics" had dislodged some of the fuses while conducting the service! On Monday, my BMW (Peter professes to be a German car expert) developed problem a few blocks from home. Because Peter is around the corner I decided to give him another chance and phoned him. He said he would come and have a look. In the interim, I phoned a good mate of mine, Ross Duncan -- who is also a BMW mechanic based in Midrand, and one I would highly recommend -- and explained my problem to him. He said it sounded like the fuel pump had packed up. This was also Peter's diagnosis on arriving at my car, but he said he would have to tow it (6 blocks) and put it on the diagnostics machine, after which he said he would phone me. Three hours and three phone calls from me later, he finally got back to me to say it was, indeed, the fuel pump but that they were difficult to get hold of and cost R5500 for the part alone. I told him I would get back to him and phoned Ross, who said they were a "nett" item at BMW, there were plenty in stock and they cost R3500. I phoned Peter back with this news and he confirmed he could get one for R3500 but the total for the job would be in the region of R6000. I asked him why and he said labour, towing and diagnostics (which he said took 2 hours) made up the balance. He towed my car for 6 blocks and Ross confirmed he charges R300 for diagnostics, which takes 30 minutes, and to replace the fuel filter is a matter of lifting a seat, removing a bolt and exchanging the old one for the new one, a job he said takes "10 to 15 minutes". The bottom line is I don't like being ripped off. I have put the word out to my mates and none of us will ever use Peter again, which means he lost about a dozen customers in the space of a day!