Should I sue them to get my rights? What are my options?
Well, ultimately that is up to you to decide - we cannot tell you what to do.
However, as you describe it, it seems you have exhausted all other options.
In general, not paying promptly (no matter whether it's salaries or open bills) is a huge red flag for a company. It usually means the company is on the verge of bankruptcy. Some manage to turn things around, but the outlook is not good.
In addition to that, the company does not show any signs of trying to make things right (such as paying at least some outstanding wages).
You should probably write one last, formal letter to inform your company that you are waiting for payment, what exactly you consider outstanding and why. Send it with recorded delivery or registered, and ideally with a witness present, so there is proof.
This notification is also usually a prerequisite for suing in court. Set a time limit for a reply (14 days is common).
If that does not make them pay, it seems that suing is your only option if you want to push this further. Whether the effort is worth it is up to you to decide.
Generally you should not agree to wait longer than 14 days, no matter what excuses the company has. If they try to delay you with promises like "we need to sort out some problems" or "we are waiting for a big payment", ignore them - promises are not worth anything in this situation, and if you wait longer, the company may go bankrupt, which will make it even more difficult for you.
Learn about your options:
- Is there some sort of arbitration system, or will you need to sue in court?
- Will you need a lawyer?
- What will the cost be for suing?
- If your employer formally declares bankruptcy, it may become hard to recover anything (again, depending on local regulations).
Consider this, then decide.