MiWay puts pirated used parts on my car!!!!!!!!!!!!!!!!!!!!!!

I cannot believe this, I have been with Miway for years and this is my first serious claim. I went to collect my car from renew-it Rivonia (Never take your car there), to my horror, I found that they have replaced my bumper with a used plastic pirate bumper that look like it had been picked up from the s****yard. Renew-it Rivonia, told me that miway instructed them to not fit original BMW parts, but seek “alternative” solution to repair my car. Please tell me where in your policy schedule does it state that you can use pirate parts on my car, you are saving costs in the wrong way!!!!!!! This is after two months my car been at the renew-it Rivonia. I am still waiting for miway to get back to me after I have requested one of the senior manager to call me. Please fix my car properly with genuine new original parts. This is pathetic, I honestly did not believe that Miway could do this to me.