Airtel — inappropriate billing, bill to be reversed

Address:

C-404 AMBIKA APT, SEC-20, NERUL, Mumbai City, Maharashtra, 400706

I had changed my plan online to 649 monthly rental on my number [protected] where we can have one add on number free for lifetime. I tried to add my alternate number [protected] but was unable to do it online, so i called the customer service spoke to the rep and was told that they will add the add on number. I had gone out of mumbai for 2 months and when i came back i was shocked to see that the number was not added and i was billed seperately for both the numbers inspite of having the 649 plan where we get a number added for free. I have been talking to the customer service and no one is even willing to understand the situation.
I want the bill for the add on mumber waived as i am already paying a higher rental of 649 on the primary number for add on services