i am using blackberry 8520.sometimes when i surf the Net with the wifi, at the end of the day when i checked my prepaid balance, it turned out to be zero cent left! this is frustrating because, i have already set the browser to use hotspot browser instead of WAP. please advice.
The 8520 can be controlled to stop the cell access to get to the internet by setting options. Apparently you are not setting these correctly. One simple test can be to turn off all data function and see If it helps This is the guide for the 8520.
BB8520 wifi problem: it eats my prepaid value! 
