Forcing renewal upon the expiry of a limited employment contract

I was working with a company in Abu Dhabi since 2014 and successfully completed my 2-year limited contract.

Now, I sent a non-renewal letter to my company after finishing my contract, but they are forcing me to sign one more contract and not releasing me by saying that I am supervising many projects and I cannot leave suddenly.

It is very important for me to go back to my country and solve my personal problems. kindly suggest, what should I do?

I have already booked a complaint against them in labour but I am worried that through labour dept. it will take time as my employer always skip court hearings.

Kindly suggest and also correct me if I am wrong, do the employee in a limited contract need to give notice period before the expiry of work permit?