Airtel — airtel number disconnected without information

Background - i have a prepaid connection number. I noticed that few days ago there was no signal connectivity on my airtel sim. I tried changing the sim on different phones but to no effect. Consequently, i visited the airtel office today to understand the issue. I was told that the number has been disconnected since dec 1 due to no activity on the connection. I asked if this can be activated now, i was told that it cannot be activated now.

I understand there was no outgoing call made on this number, but i had been receiving usual sms's / incoming calls. Thus the number was "active".

Concern - i would like to understand why was the number disconnected with no communication to this effect. I have tried raising with the nodal & appellate authorities of airtel as well, unfortunately, have not received satisfactory response so far. They have a very generic response, it looked like i am speaking with some customer care executive and not appellate officers.

Support required -
1. Activation of the number asap.
2. There were around ₹200 amount balance in my account. I would want the same reinstated.

P. S: mobile number / email id's have not been mentioned here. Please let me know the email id / mobile number at which i can contact, i will be happy to provide all the information.