Has anybody got similar problem as me?

I had a problem to buy HH on Steam - it showed "Your transaction failed because you are trying to buy a game that requires ownership of another game you do not currently own" (I've got boxed F:NV) - so friend bought me DLC.
But it's still doesn't work - HH is not even listed on F:NV DLC list. I reported it to steam support and finally got this answer: "We are still investigating this issue further with the publisher".

Who has to be blamed? Bethesda for low quality or Valve/Steam for crappy service? And what with next DLC's ?