Im sorry to hear about your story. But as far as Qatar Labour law you have the right to claim the end of service gratuity especially if its stated with your contract you the contract. The good things is you have secured the NOC from them now you can find any job around atleast. You can seek advice from the labour in Industrial area.. If they Labour arbitrator cant arrange the payment in labour the case will goes to court which will take time to process unless if you are really eager to get you will have it. They cannot escape the law.