Poor servicers

I bought a turbo for a golf 5 TDI TURBO failed and took it back to Boss auto spares I was told it was taken back to the supplier a month later still no response from boss auto spare so I decided to go to the shop on my arrival I was pointed to the manger who told me he did not wanna get involved and refused to help me .a month later I have not been helped and paid 12000 they refuse to replace the part or refund me as the part had a warranty