Problems with sky sports

[Divided12]

Hi all, 

I have the full sports package but every now and again when I go to view a channel it says to watch this channel I need to upgrade my package. I've spoken to people at sky about this 3 times now and each time they tell me to reset the box and do a callback on the card, whilst they resend the signal to say I do infact pay for this package. After that it works fine for a few weeks. 

Does anyone have any idea how to stop this happening constantly because it's getting incredibly frustrating.