Sold me broken hardware, refuse to replace it

Graphics card stopped responding, took it to Matrix Edenvale to have it tested. Was told it's most likely the motherboard PCIe slot. This motherboard was bought from a different Matrix branch 1,5 years prior, and still under warranty. Motherboard was sent in for evaluation, but I was told that the warranty is void as one of the pins was bent, which caused only the PCIe slots to stop responding... so I was then required to buy another motherboard. Matrix Edenvale had no motherboards which supported my cpu so it was suggested i buy a new motherboard AND cpu, which I did. This motherboard was brand new, and was assembled on-site by one of the Matrix techs and tested ie. the PC turned on. Took the PC back home, plugged everything in, noticed one of my hard drives wasn't working and checked the SATA connection. THE WHOLE SATA CONNECTION HAD COME OFF THE MOTHERBOARD. This was a brand new, out-the-box motherboard which was assembled by THEIR tech. So i took it back, asked Matrix to send it back and replace. 2 weeks after sending it in to \Local Suppliers"";only to have them tell me that my warranty is void on this motherboard too. TOTALLY UNACCEPTABLE"""