Airtel — my cell phone is not connected to internet connection when changed from 3 g to 4g sim card from 21.11.2019 reg-requested to connect to inter

Address:

Coimbatore, Tamil Nadu

I am having 3g cell phone. Due to the message from airtel to migrate to 4 g sim i changed my sim card from 3g to 4 g from 21.11.19. Whatapps is not working from the date of changing ie from 21.11.19. I request you to arrage to connect the internet in my cell. I have already made a compliant on 23.11.19 from thudiyalur - coimbatore airtel office but till date not resolved