Airtel — Landline disconnected from last 6 month

We have been using Airtel service for the last 6 years.

We have made last payment on 17th December 2020 and cleared all old dues. On top of that, we have been given by your office a credit limit of INR 19, 300.

Surprisingly, for due amount of INR 5, 400, which is charged for the month of January 2021, why have you disconnected our landline when we have the credit limit and courtesy no one has the decency to call up our office and check before disconnecting. We also follow-up with your team for reconnect our line but not getting any updates from them due this we have not paid the bill for Jan & Feb.
Your tell me, How can we pay if line is already disconnected for these month.

This is our corporate office with 50 people working and without the landline, we are facing acute problem in connecting with outside world like customers etc. Also we are not receive the any information about our landline disconnect from customer support.