Airtel — complaint against airtel store person

Address:

Bangalore, Karnataka

I have been a loyal customer of airtel from past 8 years.
In the last second week of april 2019 i went to airtel store near sony signal koramangla to get a nano sim as i wanted one for my new phone.
Mr manjunath from store told me to convert the service to postpaid to get a nano sim. I gave the required documents the same day. The sim got activated but after a month basic call (Both incoming and outgoing) and sms service got deactivated and a week later sim got deactivated.
I tried calling customer care when there was network availabe but they were unaware of the issue. Later when i went to another store, they informed the conversion procedure done to get postpaid service was illegal.
My number has been added as child to mr manjunath's number and then removed after a month and was told to file a complaint. I called this person and he requested me 3 days to activate sim. Now its been weeks and he is unreachable from every means.
From past month and a half my sim is deactivated and there is no help from airtel customer service. As it is registered number i am facing a lot of issues with bank, office etc.
And the irony is people from airtel are calling me saying there is overdue balance of 4000 when the sim is not even active.
The store is unreachable, customer service is unhelpful.