C6309

Hi mbworld new to the site I just bought a 2009 c63 2months ago just did the 10000 mile service on it and had a tranny seal replaced I got the car back today and it seems slower then when I dropped it off not sure why It doesn't pick up as fast as it did before wen I floored it before it put you in your seat no matter what RPM or speed now it doesn't I can say the car did run rich before I dropped it off could it be the owner before me had a tune that's why it ran rich idk what happened can anyone help thanks