Claiming entitlements from the employer upon resignation

Dear Sir/Madam,

I have been working in a Dubai free zone company for the last 3 years as a security guard. For almost 1 year, I have been working without any days off.

It is mentioned in my contract that I have to work 48 hours a week and 3 hours fixed overtime.

But after working for 1 year continuously, they started to give us 2 days off for 2 years. Now, I resigned from the company.

The end of service department has told me that they'll not give me that overtime.

So can you guide me how can I get my overtime?

Thank you