WORKER WORKS 7 DAYS/WEEK FROM 9AM TO 2AM, LATER RESIGNS & BOSS REFUSED TO PAY HIM

My former boss is overworking their employees. I formally resigned and found a new job but they won’t give me my required documents nor did he give my last payment.

The former company is severely understaffed. The boss doesn’t care if you can’t finish your heavy workload. Me and my former co-workers would work 7 days a week from 9am to 2am. Just to finish our work.

I formally resigned and they accepted. They didn’t give me my last pay check. The reason why they can’t pay me is there is no proof of work. But there is, it is all saved in the cloud and my co-workers are working on it. His favourite line is, “You are lucky to even have a job. There are so many jobless people right now.” He says this to everyone and every time. He wants you to feel proud by being a slave to his company.

As much as I want to punch him in the face, I always remained calm and never talk back. Because people like him has a huge ego and talking back would do more harm than good. Even as I resigned, he wished me good luck.

I found a more decent company that treats its employees like humans. But the former boss seems to be jealous or something. He didn’t reply to my request for my work documents.

What can I do to get my documents? Where can I report such unfair labour practises?

UPDATE:

1. Call finally went through my former evil boss. Passively aggressively pins the blame on me. Told me he tried calling and emailing me. But there is no record of this. He lied.
2. He still cannot issue me my paycheck because, again, he pins the blame on me because they cannot contact me. He sent me no email, text, nor call. So it is my fault he can’t pay me.
3. Current company understood the situation and waived the required documents.

Edited:

1. Already reported it to MOM.
2. However, can’t show them proof since my previous employer destroyed all evidence.
3. Employer has control of the chat, emails, and co-working software. All of our previous conversations, transactions and my resignation are all deleted.
4. I am a foreign worker. I work for the company remotely.
5. This company has an office in my country, but I work with the SG team.
6. Here is part of the contract where it says I cannot say anything BS about said company.

Edited out some details to prevent them from recognising me.