Airtel - Plan value more than real value of plan

Airtel is charging me *** for a plan which is ***. I have two airtel numbers. Both were upgraded in September. But one number was upgraded to *** and another to ***. My frds nos who were on same ** plan also had plan upgraded to ***. I contacted airtel several times for their mistake, but they are straight away lying on my face by saying that *** plan doesn't exist, whereas I shared evidence showing proof of *** plan. They just turned blind eye to it and their nodal officer kept on sending me automated emails. They even said on call that they will upgrade everyones plan to *** in future. I have the question then why was my number given special importance. Everyone's plan should be changed at same time. In reality Everyone's plan has been upgraded to ***. Despite of chasing them and sharing proof of their mistake they aren't changing my plan amount to ***. I am not ready to pay extra amount every month for the same plan. I was a loyal customer but I have most trust as they are scamming me and lying straight on my face which is totally unacceptable. Please help me change my plan or finally I would have no other option that to stop using their number.