Hi

I had this problem (BAS/ESP light coming on) for a while and regularly re-centred my steering to get rid of it. I put it down to me possibly damaging one of my wheel sensors when I last changed my brake pads and just put up with it. I was talking to a Mercedes mechanic and he said it's a common problem he sees all the time with Mercedes of the same era. It's caused by a faulty brake pedal switch. I fitted a new switch and the problem has never returned. Give it a try!