LG vx8500 and disabling HS

Hi,

I'm aware that HS must be the equivalent to the US ev-do (HSDPA), and want to turn it off when I'm not using the browser itself to save battery (since my 8500 lasts only a day or two before dying ..)

But, going to the menu and pressing 0 does nothing.. ##program8500 / ##program8550 do nothing.

The phone itself says 8500, but the backing says the FCCID id is BEJVX8500.


Any help is appreciated, thank you.