Airtel — postpaid sim is use of airtel which is giving me headaches

Address:

Meerut, Uttar Pradesh, 250001

I am using an airtel postpaid connection and my bill is overdue but am unable to pay my bill because neither the airtel app nor the airtel online postpaid bill payment website is ready to accept my number, as i go for bill payment it says that the number is incorrect and please fill in a correct number, i have been facing this problem for a while now and am totally fed up with airtel. I want to switch to vodafone bit since there's a minimum time that i gotta use this number isn't up i have no choice but to continue with this number.
How do i pay my freaking bill when even airtel isn't ready to acknowledge my number as their postpaid connection.
Where do i complaint to the highest authority for this mistreatment.
My number is [protected].