I brought my car in because the check engine light came on stating it was a small vapor leak in the fuel system. They quoted me $60 to find out what was wrong with it. Brought it in, and they couldn't find the problem because they needed to a more extensive smoke test to find where the leak was which costs $200. However they said they would deduct the first $60 from the cost and credit the total diagnostic expenses toward the repair. I brought it back for the smoke test and they stated a gasket at the fuel sending unit needed to be replaced which was a $25 part. Total cost was around $240 with taxes. As soon as I drove home, the check engine light came on again for the same problem. Brought it back for the 3rd time, and they stated there was a clamp the mechanic didn't tighten properly which caused it. Great. Soon as I drove home again the light came on again. I went back again for the 4th time and they redid the smoke test. They discover the fuel sending unit itself was leaking and was hoping it was just the gasket. They quoted $270 for the part and 4 hours of labor to change it out. They stated they would only charge me 3 hours because of the prior diagnosis. Unfortunately, I had already paid for 2 hours of labor not 1 hour, but they wouldn't give me the credit as promised initially. In addition, I found out on the mercedes forums that the problem is very common, but it only takes 2 hours to do the job. I confronted them with this and Charles denied it stating it would be a minimum 3 hour job. I went to Schumacher Mercedes dealership and bought the original part for $230 from their parts department and changed the fuel sending unit myself. I followed the instructions posted on the forums by other members and finished the job in an hour and a half easily. In addition, I also inquired about a burning rubber smell coming from the engine. They said it was the expansion plugs at the back of the engine that were leaking oil onto the exhaust - easy fix 1 hour job $200. I found out that the plugs were just plastic caps that costed $25 from the dealer and took 10 minutes to change out - simply pry off with a screwdriver and pop back in. This is what happened when I went there. Wouldn't recommend going there even if their labor rate is $98 or whatever compared to the dealership's $139 - seem to be quoting more hours to do work and not crediting what they're supposed to on diagnosis time or taking credit for screw ups.