If you are really want to waste the time and money then go for Tata Docomo. I put up the cancellation request and it took around 20 days to get cancelled and charged me for that even though I did not use it.
You have to call for 5 6 times to customer care to get cancellation done. Then they will ask you to put in safe custody without any charge and then they will send you the bill to pay.
Then if you want to go for cancellation, they will say it will take 24 hours to cancel first safe custody so you have to after 24 hours.
If you really want have pain in your life then go for Tata Docomo. I really did not expect this from Tata Groups. I really admire Tata Corporation but Tata Docomo disappointed me.
Sometime I feel like to write a letter to Mr Ratan Tata whom I admire a lot.