And send that letter recorded delivery or registered so there is third-party proof that they received it.

I've sent the formal letter yesterday and today they approached me about a 20 minutes before, they agreed they had some bad decisions and promised to pay my delayed payments and checkout with me in 2 or 3 months.

if they don't keep their promise then I will sue them from officials

@SolarMike: Good point, added.

@Mohammad_Hosseini: Thanks for the update. I hope things work out for you. If not, the option of suing remains.

@sleske Thanks for the answer and the tip, hope it don't go that far.

@Mohammad_Hosseini, 2 to 3 months? That's insane! Did you get that promise in writing? or was the promise verbal? You need to have their promise in writing. Again, you need to tell us your location.

@Mohammad_Hosseini If they will not pay you for 2-3 months why do you work for 2-3 months?

@Mohammad_Hosseini you mentioned in another comment that you heard someone talking about bankruptcy. "We'll pay you in 2-3 months" sounds a lot like it really means "we'll pay you if we don't go bankrupt."

@AntP I think it sounds more like "It'll take us 1-2 months to declare bankruptcy, so let's give them a time frame where we won't have to pay."

@Mohammad_Hosseini, read my comments in one of the other answers. With the problems you describe it is unlikely that the company will pay you anything and it seems like trying to just buy some more time. Enforce your conditions and if they don't comply take further legal actions. Otherwise, you will most probably never see your money.

@Ister (and others):Good points about not waiting too long - I took the liberty of incorporating that into my answer :-).

@Mohammad_Hosseini I would recommend checking with a local lawyer. At least consult with one. I come from Lebanon, for example, and if such thing happens there, you would need to [at least] file a complaint to the ministry of labor within one month of you leaving work or else the chances of being able to get back what you are owed are very slim if you later had to sue them. I strongly recommend you check with a lawyer if you are not extremely familiar with your rights as an employee.

@Ister Thank you all, I've talked with a local lawyer and talked to Ministry of Cooperatives, Labour, and Social Welfare in my city, it turned out in my country the employee will win eventually and all organizations agree if you have delayed payment, the company or corporation you're working for will get punishment eventually. so it's better for them to pay instead of ignoring or doing anything otherwise

@Dan thanks, check the above comment.

@Mohammad_Hosseini, That's great news! In the US, it's basically the same thing. The Department of Labor does all the work.

@StephanBranczyk Yeah, That's such a relief. Thanks for all advices.

I'm out of the company for two days, and I've updated my social media status about leaving my workplace, and goodpoint is that I'v had about 5 different job positions till now. why I didn't came out sooner?

@Mohammad_Hosseini, You should post your own answer with the information you received. Then, you should press the checkmark next to your own question to accept it as the new answer (instead of the previous answer you had accepted). This will ensure that if anyone from Iran has the same problem, they will know the right solution to the problem.

@StephanBranczyk Sure, I'll do that.