Vodafone India — asking for extra bill payment by threatening

Address:

Bangalore, Karnataka, 560032

I had been using vodafone number [protected] few months back.

Then due to network issue at my location i opted for portability to jio.

Vodafone cleared informed to clear outstanding balance and then only i can change to other opertor.

So i cleared the outstanding and switched to vodafone. (Paid bill attached).

Now after 6 months vodafone is sending mail and calling through third party asking extra bill payment.
I have mailed them so many times about this concern and also shared paid bill. But still they are threatening to pay the bill