BB Curve :: BIS No Connection Without Wifi

so my next post. i reported some problems previously about my phone about BB app world not working unless its on wi fi as well as facebook and it specifies as something to do with service provider and data plans as problems, which they say everything is alright. as its too late for phone vodafone i thought i would try here first.

everything on my phone is working fine (BB messenger, emails, browsers, texts etc etc) but like i said app world and fb arent. App worlds works perfects whilst using wifi, but as soon as theres no wifi it stops working.

i found out that when i turn the wi fi off on the manage connections part and check the service status, under Blackberry Internet Service it says no connection. and im unsure how to change this. When the wi fi is on it says 'connection: wi fi'. and i was told when i turn this off it should turn to my service provider (vodafone) but it doesnt. so im guessing the main problem is something to do with this.any way to get it working