Hi bigmacus
Welcome to the eForum!!
If you have canceled a modem SIM and not migrated it to PAYG then you will be unable to use this SIM card to top up. Unfortunately you wont be able to just by a data SIM from Vodafone as they come presold with our modems, and not separately.
If you canceled this down and migrated to PAYG but have not topped up inside a month then this SIM would also be disconnected.
Have you tried putting the SIM in a vodafone phone and seeing if it loads up as vodafone or as SIM rejected?
Thanks
BenJ
eForum Team