Reliance Arc — Noc provided after ots and still asking me to repay the remaining educational loan

Hi,

Ive taken education loan in the year of 2011 to 2014. Total loan amount was 1, 49 000. During this period before giving the loan amount they have asked to pay the interest for that year, after paying interest i was getting the loan amount for every year.
After completing my degree, in 1 year i started to repay the money, but after few months it got transferred to reliance ARC and i started getting calls asking to repay the loan with OTS. Initially i was not agreeing, later they asked me to pay only 25k as one time settlement to close the loan. I agreed for that and paid the money in reliance ARC account, after that i got the noc letter in email by cc ing sbi branch mail id.

I thought its done, after 2 to 3 year, again they are coming back and qsking to repay the loan amount.

Everytime its different different person, if i send noc few wont come back..now they are telling that the noc is fake.

Whom i should believe now?
What should i do now?
The loan is in my fathers name, they are getting calls and messages frequently.

Please let me know how to take it forward.

Thanks