Help needed Polishing a 135i

Need help from the Pro detailers,

My white 135i has some scratches from I think getting washed with a contaminated sponge at a garage and I have tried but cannot get them out.

I have taken the car to a company in Paarden Eieland CPT and the guy phones me and tells me he cant get all the scratches out and he is scared he will damage the clear coat.

He tells me that BMW's in general have poor paint and it is very thin, my question is how far can one go to get the scratches out.

how thick is the paint? and what can we go to?

thanks

Dax