XFX problem

Hi Guys

I was given a HD6770 XFX Radeon 8 months ago for a present now after raising the money I bought an ASUS m487TD USB3 Board with Hyper X RAM I fitted the board and memory with the 6770 and I got no display and post bios error, I then fitted my old 9400GT and it worked.

I went to XFX because the suppler is no longer in business closed around 3 months ago but they will not RMA or repair but the offer me a Upgarde giving 16GBP towards a new XFX card now I never have fitted the card until now it is still new
but still the offer me this feeble amount DO NOT BUY XFX AT ALL COSTS

My System is

ASUS M4A87TD USB
Kingston Hyper X 4GB Ram
GE FORCE 9400GT 1GB PCI-E
Windows 7
LG 21 LCD Monitor
ACE 750W PSU