Airtel — I am not able to use VoLTE service of Airtel since I port in my Number in Airtel.

I ported in my two numbers in airtel in family plan (I have two number + Airtel DTH). Since I ported in into Airtel I am not able to use the VoLTE service of airtel. I reported on 21 Sep 2020 regarding the issue and expected date was 29 Sep 2020. But issue is remained same. after this expected time was extended two time 3 + 3 working days but issue is remained same.
An Executive suggested me to replace the SIM, I did that, I replaced the SIM last week but issue is still same.
I called to 198, then executive told me that our technical team tried to reach you but you did not respond.
And executive told that SIM is VoLTE enabled but when I insert this sim in my mobile there is no option to enable VoLTE call, while I have a prepaid SIM of IDEA, IDEA SIM shows me the option to enable VoLTE call.
Why it is not available with Airtel SIM, are you sure that you are providing VoLTE service or are these services are specific?
During the call I am not able to use my mobile internet, as you are aware mostly peoples are working from home and phone and internet is a lifeline these days.
Due to this disconnection of internet during the call, I am using another phone with prepaid SIM and have spent extra money for the calls only while I have a good plan of Airtel with platinum member ship.
Why I spend extra money for call?
So, finally my question is this only when this issue will be resolved?
Will it be resolved before I port out to another operator?
Actually, I can't give more extension on this because you have taken too much time to resolve this tiny issue, I need the solution ASAP.