Regarding interest of outstanding dues of employee

I was working in a PSU. I had to leave the job as I was suffering from lumbar sacro disc problem coupled with pressure from the organization to join back. I have resigned online, which they accepted retrospectively, condition of 1 month salary and any outstanding dues (which I considered nil).

When I approached them after 3 years, they informed me of an amount 5 times my 1-month remuneration and around 50 documents (not listed). However, my query of to whom to pay was left unaddressed by them. Also, I filed an online transfer claim application to my new employer's PF account.

Till date, I never received a demand letter and last month, after filing CPGRAMS for non-transfer of PF in the last 3 years, I got a call that they will charge interest on dues and question on documents left unsolved.

Please provide information on whether they can charge interest without providing me the information related to total dues. If yes, then which time period will be considered? Also, they maintained a PF trust with them, they refuse to provide me PF without the settlement of dues. What is needed in such a situation?

Query is not clear. "I have resigned online, which they accepted retrospectively with the condition of one month's salary and any outstanding dues (which I considered nil)." Have they given written acceptance of the resignation? What you consider about outstanding dues is alright, but what is the record of PSU about loans, advances, etc.? You will have to write the query more clearly and chronologically for better answers. Why you waited for three years is also not clear?

Resignation was accepted in 2013. As there was no communication from them regarding my dues, and I also considered that my one-month pay would be adjusted with PRP (which they provide), I had to withdraw my savings from their trust. I approached them for a demand letter. Even today, while asking for the demand letter, they got annoyed at the mention of it.