Why can't I use my subscription unless I wipe my phone

I have this problem everytime I buy a data plan on my blackberry9800 touch,I can't use d data unless I do a security wipe nd its killing me,because I have to wipe all d datas on my phone including d media files ......pls help me

The 9800 uses BIS so I'm unclear on what exactly you are doing to keep buying a data plan.