My happy has reduced my basic salary from 900qr...

It should be noted that after reviewing your inquiry and legally verifying it, we would like to point out the following and, in accordance with Qatar labour law, the matter is considered a violation by the employer, especially since the contract is the law between the contractors, and therefore the work is not allowed to reduce the costs agreed in the contract. Consequently, it is possible to go to the Ministry of Labour and Social Affairs and leave the work in accordance with the provision of article (45) of the law, which stipulates that the employer may not assign the worker to perform work other than the agreed work, except to prevent an accident or to repair what has resulted from it, or in the case of Force Majeure by giving the worker the rights resulting from it.
As an exception, the employer may assign the worker to work other than the agreed work, if it is temporary or if the work does not differ substantially from the original work, and the assignment to that work does not involve abuse of the worker, and provided that the worker's pay is not reduced.
*** As stated in Article (51)
The worker may terminate the service contract before its expiry. date if the contract is of a definite duration and without giving reasons for the termination if the contract is of an indefinite duration and retains his full right to obtain the end of service gratuity in the following cases:
1-If the employer commits a breach of his obligations under the service contract or the provisions of this law.
2-If the employer or his responsible manager commits a physical assault or immoral act upon the worker or any of his family member.
3-If the employer or his representative has misled the worker at the time of entering into the service contract as to the terms and conditions of the work.
4-If continuance with the work endangers the safety and health of the worker provided that the employer is aware of the danger and does not take the necessary steps to remove it.
*** Therefore, with the submission of a complaint to the affairs, you can also claim the wages due to you, article(66)
The wages and other sums to which the worker is entitled shall be paid in the Qatari currency.
The wages of the workers employed on an annual or monthly wages shall be paid at least once in every month.
The wages of all other workers shall be paid once at least every two weeks.
The wages shall be paid to the worker himself within the working day’ and during working hours in the usual place of work or any other place to be approved by the Department and may be transferred to the account of the worker with the bank to be agreed upon by the two parties or paid to the attorney appointed by the worker in writing.
The employer shall not be relieved from his obligation to pay the wage due to the worker unless he has actually transferred it to the bank or the worker or his attorney has signed in acknowledgement of the receipt thereof in the register or receipt prepared for this purpose provided that the said documents shall include the details of the wage.