Thanks, seems I really do need a lot of luck to resolve this issue considering nothing else seems to be working. I don't have any idea on the timelines by which to expect a reply, but hope they do take action on the grievance whenever it is. Also, I sent another follow-up mail today morning to the nodal officer and included the Appellate Authority in addition to TRAI, but don't hold much hope of Airtel acting on its own.
Still no response from anyone. The Appellate e-mail address for Mumbai does not even work anymore. The entire freaking customer grievance system seems to be a joke.