Product ok Seller: Stay away

The graphics card performed the work that is required to make a graphics card just, well. Mounting and installation problems and possible within 15 minutes, the card has been detected immediately. The image on the monitor HP w2207h leaves no wish unfulfilled.
However, 1 month ago warranty end joined to a defect in the fan card. Then I contacted the seller (CM3-Computer OHG) as follows:

"Dear Sirs,

the fan of the GRP is defective (was checked), at boot
Computer are the fans of the GRP is a whirring not listening to sound. This noise came first 5 min., And now up to 10 min.
I ask for feedback. Many Thanks.
Yours sincerely
XXXXX "

The answer was as follows:

"Unfortunately, it's not as easy as you bought your ticket on 8.1.2010.
You bought the goods with a 24 month warranty (See invoice /
Offer). Warranty is not guaranteed. That is after 6 months the returns
Burden of proof. You would need to prove that the goods on delivery
already a defect aufwiese which now led to the present defect
has. For this we need a recognized certificate. You can also take in
Inform Google.de or other source about it. "

Advice / tips on what the failure is, or how he had to fix, we were unfortunately in vain. Noteworthy is the offensive tone, especially since we no similar claims for Exchange had asked. Apparently, the seller has good reasons to quash any claims, without these being ever asked?

A constructive dialogue is with the trader does not seem possible, customer-friendly assistance and cooperation for problems you will miss. Therefore our advice: Stay away from this seller.