The stay x get x codes seem to be incorrect:
I started with 2222; this code was already showing up not eligible in my account - this means it is (most probably) an old code, maybe for Q4-2010.
Then, I advanced to 1601 - this worked fine.
I furthermore tried 4741; this ALSO went through, which, to my opinion, means that either you collect points for both (which is extremely unlikely), or - that seems to be the case, one of these codes has already expired.
The 7595 and 8579 were n.e.
Anyway, none of these codes unfortunately show up on the offer status
