if u want 2 stop postpaid connection switch to prepaid with Rs 98 recharge with 1 month validity and Rs 9 talktime, pay current and outstanding dues. Use it for 1 month and then throw the SIM.
I done this quite a few times since I have a transferrable job.
It is time saving and also helps on not to go to customer care people, only once you have to go to retail shop for conversion to prepaid along with supporting documents.