had a lovely conversation 2day...

on the phone with scan computers. i recently sent my Graphics Card back due to it not working properly. this cost me
Flight Simulator and other chat
https://forums.simviation.com/phpBB3/
https://forums.simviation.com/phpBB3/viewtopic.php?f=9&t=25068
3dmark_06 is not a video and it does stress the card, so much so in fact that any weakness will almost certainly show itself as a crash or error using the program, I use the program to test max O/Clock settings on video cards and it definitely will show hardware limitations with an error messgae or full blown crash.
If the repairer tested the card using that software and was satisfied that the card was not faulty, you should understand why they would be annoyed for having their time wasted by someone with other problems who is blaming it on them.
If it were my company, I'd have an extra service charge for people like you who wasted my time.
In any event, it sounds like your problems lie elsewhere, and, even if the video card is the problem, perhaps it's only an overheat problem in YOUR particular installation which did not show up when tested on the bench rigs at the repairer's workshop.
Is it only one game these problems show up in? and what are the problems you are having?
If you and them both ran 3dmark and it showed errors it is very possible that the problem lies elsewhere than the card itself, could be the game, drivers etc...