Incorrect Transmission Fluid

[SLickmann]

I'm new to this forum and I'm hoping someone can help with this. I have a 2000 S500 which gets serviced regularly at an independent Mercedes shop. He recommended a transmission flush when I recently took the car in for regular servicing. The car has 55k. I assumed he would put Mercedes transmission fluid in, but found out afterwards he used some other brand. It was BG brand I think he said. I was told it was just as good and was a much better price. I'm concerned this is not the right fluid and it should have Mercedes fluid. Should I have another flush only this time with Mercedes fluid? Does anyone know if this BG fluid will damage my transmission systems?

Advice on this is much appreciated.

S. Lickmann
Michigan