Pls. find below Article 73 of the Qatar Labour Law about the working hours.

"The maximum ordinary working hours shall b e forty eight ours per week at the rate of eight hours per day with the exception of the month of Ramadan when the maximum working hours shall be thirty six hours per month at the rate of six hours per day."

First you can send a letter to your manager quoting the above article of QLL and you can claim daily 2 hours OT also.

If they are not not responding positively, you can lodge a complaint to Labour Dept.if you are ready to fight with them.