Airtel — Prepaid Sim deactivated without warning 2022

I had used MNP to move my SIM from Vodafone to Airtel in Feb 2022 in the Bihar Jharkhand circle.
I had an initial recharge of 1 month in February followed by a recharge of an year in March 2022. The validity for this recharge was till March 2023.

Suddenly Airtel has deactivated my number and when I contacted their customer care team, I was told that they cant help as the number is not with Airtel. The number was active till end of April and has suddenly stopped working. The last recharge was in March 2022.