Your post is confusing. Your housing/transport allowance is 15000. Is this in addition to a salary or inclusive of your salary? If it is inclusive you should ask the person who interviewed you to live on that. 5000QR enough for a family of 4 to live on for one month?
Whoever told you this must be on drugs and living someplace other than Qatar. Housing here is still a drain on many people. Still exhorbitantly expensive though it has stabilized. Most landlords still asking extortionate rates. What do they care if you are paying 60%-70% of your salary towards housing. Its still very sad situation.