Caculating end-of-service gratuity

I would like to know how the end-of service gratuity is calculated and whether it is calculated on the basic salary basis plus housing allowance overtime hours and whether the said salary is calculated which mentioned in the employment contract or the current salary. Please advise me, thank you.

Article no. 134 of the Federal Labour Law No. 8 of 1980 states the following: “Without prejudice to the provisions of laws that grant pensions or retirement benefits to employees in certain firms, severance pay shall be calculated on the basis of the wage last due for monthly, weekly and daily paid workers, and on the basis of the average daily wage referred to in Article 57 hereof for those paid on piecemeal. The wage used as a basis for calculating severance pay shall not include whatever is given to the worker in kind, housing allowance, transport allowance, travel allowance, overtime pay, representation allowance, cashier’s allowances, children education UAE Labour Law 29 allowance, allowances for recreational and social facilities, and any other bonuses or allowances”. So under the article mentioned the current basic salary will be calculated only.