Kotak Mahindra Bank — harassment by their officer.

Hey,
My dad took a loan from fullturn india pvt ltd of rs. 260000 @ roi 14% and the no. Of emi's fixed is 49. My dad paid 24 emi's and suddenly the news occurred that fullturn india is gone from india.
And after 6 years. I get a call from kotak mahindra that your father have taken a loan from fullturn india and you have to pay all the dues in 2-3 days,
I said that okk fine i will repay my 25 installment in 25 months, they said 'no pay full amount in 2-3 day or in only 2 installments.
When i request them to give me sometime, so that i can arrange the money.. They said no.
And after 2-3 hours, they called my relatives (I don't know how they get their phone number) and said that you know that person (Me) then you have to pay the whole amount otherwise we'll suit a file and got arrested and many more unfaithful things.
My relative called me and asked me about this and when i called to that officer of kotak mahinder for these things. He said we'll do the same until you will not pay the full amount.
I'm depressed right now. Please help consumer forum.