Call them on the phone at 198 (free) or 121 (50p per 3 minutes) from an Airtel landline or mobile.
I did this today. I really felt bad as I love Airtel and it has been perfect for so many years.
What is the highest speed you are getting on torrents? Mine hasn't gone above 3.5 while on Airtel I used to get around 5MBps. Other downloads do touch around 11.5 though.
I mailed them at 121@airtel.com requesting cancellation yesterday. Got couple of calls from Airtel team today with good offers to keep the connection but insisted on cancellation. So, its approved and will get cancelled within 7 days. Their retention team is good and polite and the experience was good. Had 0 issues with Airtel since I got it in September last year. But, Jio being free for now doesnt makes sense to pay 1200 bucks every month to Airtel.
Torrent downloads usually hovers around 3-5 mb/sec with occasional touch ups to 7. On Airtel I used to get consistent 3
mb/sec.