I'm not from TBS
And not all 6925 are defective, I have friends with 6925 that are still working fine. It is clear that if somebody got no problems - just simply don't write at forum, but it is just using the card.
There are warranty rules for all cards - if card is still covered with warranty - You have rights to enforce shop to replace card - this is Your right and You don't need to wait for any discount. If warranty has expired, it's really only good will from TBS to offer some discount (driven by fact that of course too many 6925 are failing with DVB-S2 after some time - but not all of them).