Is there an option to prevent data service to start on its own?

[New Daddy]

I don't subscribe to a fixed-rate data plan, so it's really a pain in the *** when my XV6700 initiates data service on its own when a (free) WiFi is temporarily lost.
In such situation, what I would like to happen is a notification that "WiFi is lost", instead of XV initiating data communication, which will jack up my monthly bill.
Is there an option that will do this?