Claiming end of service benefits and delayed salaries upon resignation

I worked for my previous company based in TECOM, Dubai (Free Zone) for 3 years, during which period we had a lot of salary delays and got accumulated over time.

By the time I resigned, 4 months and around 3 weeks salary were pending along with my settlement amount. Usually, all the amount need to be settled before the visa gets cancelled.

But they convinced me (verbally), since there is no cash with the company at the time, that they would pay my pending amount as and when the salary is processed for the rest of the company.

For that, they gave me a signed letter mentioning the total amount that the company owes me; but since my departure, 2 salaries have been processed in the company and I am yet to receive any.

I have been regularly following up with them by mail and have only received "wait" response so far. Does this amount to cheating from their end? What are my legal options?

Note: The company has been sued before for similar cases regarding payments by ex-employees / suppliers.