If you know anybody working for some reputed company here in Doha, these companies usually have a corporate agreement with some 5 star hotels for their visitors and they usually get upto 50% discount and he would be able to help you get discount through his company.

The company I used to work in Saudi Arabia had agreement with Holiday Inn and Hilton and I used to travel alot and they had offered us 50% discount on room tariff and some 10% on food. This practice is very common in all the 5 star hotels all over the world.