SBI Credit Card — collection agent collected the settlement amount and the account is not yet closed

Address:

Chennai, Tamil Nadu, 600099

Dear sir.,
This reminds me a proverb in tamil
கொடு கொடு உன் மடியைக்கொடு ந்னுட்டு
குட்டி குட்டி பணத்தைக் கேட்பாங்களான்

Come show me your bag i put mangoes (As if it is free)
Then they ask for money hitting your head, again and again,

One day i was filling petrol to my bike at that time one sbi salesperson came to me and asked for my other credit card statement saying that i will get you, credit card. He did not even collect any application from me for that card.

Then they created an account and i was paying the bill s received but how they have shown due i don't know
Almost 20 years back, for a small amount of due
Collection agents called me, visited my house and tortured to the most.
Remember in those days there was no mobile.

Then at annanagar one collection agent collected money and said this is
Settlement - at that time i was not knowing what is settlement means.
In fact, the settlement word itself i came to know that day only.
He collected cash and then there were no calls, no visits and i thought
It is over.

After 20 years someone is calling saying they are calling from sbi and
Says that account is not closed.

1. Why they did not inform me earlier?
2. What happened to the money i paid?

How to trace the collection agent who collected money?
And what is the way out for this?
Please guide me.

Chennai right survey