BT Prepaid Mastercards

Do the BT prepaid Mastercards have any downsides? Can you just spend up to the limit and then perhaps stop the card without incurring further charges?

It has been a little while since I've used one but yes, that is exactly how they should work. They aren't a credit card but a preloaded payment card. Once you have spent all the money you can either top it up (not sure why) or just shred the card.