Unable to Switch off my 3G after Ios7 Upadate

Hey everyone. I have updated my iPhone 5s to iOS 7.1. With my iPhone 5s I had previously turned 3G off and left the data on. I never applied the Airtel carrier update that changes the radio options from GPRS/3G to 3G/4G.
As 4G is of no use at the moment. I have been using GPRS passively (for iMessages, , bbm, whatsapp or any other low data background tasks). I turned 3G on manually in order to use Safari and other high data demanding apps.
The reason I did this was to preserve battery life and to get better cellphone signals. And it worked. Sadly now the lowest power setting 3G instead of GPRS/2g as before.
So I restored my 5s in iTunes and restored from a local backup. Sadly again the 3G/4G Airtel update returned, without asking me!!!
Am I missing a trick? Has anyone set there 5s up as a new device since 7.1 and got to keep the original GPRS/ 3G?

Please help as I find that my battery is quickly getting drained out and I get very very low Phone Signals!