Airtel Communication - Unacceptable response of customer support team

I've been using Airtel fixed line/broadband services for the last six years. I've been experiencing low internet connection speed & frequent disconnection for the last few months. I decided to register my complaint on **th Feb'**. The technical support engineer was scheduled to come on **th Feb(*:** am-*:** am). He called upon **th saying that he got late due to traffic & while I received an sms for the re-scheduled visit saying that I wasn't available for the appointment.
He came on *st Mar:
* The connection which was working before his visit with low speed/frequent disconnections stopped working completely post his repairs.
* He said my modem will be upgraded only if I switch to a more expensive plan(While the customer care executive had given me the order ID & Order no for a new modem on **th).
* When I told him that airtel should improve its services considering the competition, he said there's no other option available in my area
Since my connection stopped working post his visit, I again called up at customer care on *rd Mar & was assured that my complaint will be resolved before *:** pm on the same day. No one turned up. I made a call to customer service again today, i.e. *th Mar & was assured of resolution b/w **:** am-**:** pm today. No help came. Why should I pay the bill of Rs**** every month with such sick & pathetic services? Shame on Airtel customer care team.