Airtel — Airtel disown my prepaid number

In the month of October, i did MNP for my number [protected] from vodafone postpaid to Airtel Prepaid with 299 recharge and it was successfully ported and working fine.
on 10th November, i did second recharge of 99 rs for another 28 days. so it was supposed to be valid till 8th December and till 30th December, we received message to recharge the SIM.
on 6th, when i tried to recharge it then Airtel website or App is saying that its not a valid airtel number.
I called Customer care and they are saying that they dont have any detail about this number.

I am using this number at multiple banks, aadhar card etc and I am in germany on deputation and will be back after 1 year.

I am looking for my number back and it should be allocated to me back.
So Do the needful asap.