I put in a claim for a replacement of my cracked windscreen,it was approved and I paid the excess amount

I put in a claim for a replacement of my cracked windscreen,it was approved and I paid the excess amount. On arrival for fitting, they came with a pirated second hand windscreen (you could see the marks from a peeled off vehicle disc). Mind you I am covered for comprehensive retail and my car is still under warranty which means only original parts can be used on my vehicle. I then called the insurance to raise my grievance and they have been giving me the run around. They lie that it has been authorised on their side but the glass fitters say that it’s the pirated one that is approved on their side. They still refuse to give me a solid answer with regards to this authorisation issue. I have not been helped and they racially profile☹️