The solution couldn't be really more simpler:
Value 2 bed room apartment =8000QAR
Value 3 bed room apartment=10000QAR
Value Villa 12000 QAR.
Let the guys make a choice and everybody is happy as well as QR will save money. If Cpt wants to take a two bed room one he'll get 4000 QAR refund or if F/O wants to take a villa he's gotta pay 2000 QAR on top. As easy as that. I believe it's called resourse managment. Ranking does matter but if someone is alone or single and wants to save money why not to give him that chance? For the company it's gonna cost all the same anyway but the accommodation won't be half occupied, as it's the case now, thus doubling costs. Folks would be happy and that's not acceptable in QR. Anyhow it's probably too much to expect.
Don't take it personally take it on the rocks!!!