BB Curve :: Block It From Accessing Gprs?

i have d bis service activated on my new curve 3g (full service)recently i have started noticing that my balance is geting deducted every now nd then so i decided to ask the operators whr is d balance geting deducted they tell me that i have been using gprs on my blackberry why would some1 use gprs when 3g bis is activated it dint make any sense to me so i decided to go to the nearby service center and there they tell me that since blackberry is a verry advanced phone it keeps trying to acces gprs even though bis is activated he suggested me dat there must be some 3rd party app which is trying to use gprs!so he suggested me i remoove all 3rd party apps and check if the same is happening! and i did so, since then for 3-4 days balance was not geting deducted!

since 1 week i have discountinued with the service for some reasons and i have noticed that the balance has started geting deducted again ! and it follows a specific pattern every hour at exactly 4 mins passed (10:04 , 11:04, 12:04) the handset is trying to acces gprs i mean there r no 3rd party app installed on my fone except for foursquare, google maps, and bloomberg mobile!
i read in some other posts in the forum that there is some app which tries to use gprs backdoor!and since yesterday randomly my bb starts giving sumnotification sounds when i chk 4 any notificatin it is not showing anything!