Topping up prepaid cards not working very well.
The past few times that I’ve topped up my card it sticks on the payment page after payment. (Same with everyone else I know) The only way out is to click on cancel, but the payment is credited anyway despite what the app says. Just be careful not to pay twice! The credit however can take a while to be added so don’t leave it until you really need it, you could have a wait.