Company not giving release letter - charging INR 50000 for these documents

Actually I am in a trouble. I stopped working in my previous company since my salary was due for 3 months. But the mistake I made was that didn't send them any formal resignation letter. So they took that advantage any sent me a termination letter intentionaly. I didn't bother at that time since I got the job in my current company but now when I am going for the interviews they are asking for the release letter/Experience certificate or the payslip of previous company which I don't have . I tried to contact my previous company but they are now charging INR 50000 for these documents what can I do now.

You should take this as a lesson and dont repeat these type of mistakes again in future. Small things will back stab you.
Go and meet them and compromise them. You may say that you will support them in their projects or will provide training for their freshers.. etc.., or You can demand them for 3 months salary which was pending. come to a joint settlement and get service certificate in hand return home. Just pay Rs.10k if required and get things done. You can earn that later.

Thanks STEPHEN_7 for your advice.As you mentioned I have already talked to them but they made it clear to me that that they will give those certificates only if I pay them 50K otherwise not.

Actually during these two years I also used to do some work for my friend's company. But I don't have any official letters . So instead of showing this company's experience can I show the experience of my friend's company . In that case I can get all the documents from him and I have also actually worked for him. So if I write that experience(friend's company) in my cv then in the background checks will the name of the other company be revealed and will my experience be treated as fake??