Telkom Fibre prepaid top-up error

I have been trying to top-up my data on Telkom for the past week now, but for some reason I can't do so. Everytime I get to the final screen after entering my credit card details, the interface keeps failing or says that the payment is not authorized. Please can someone from eskom sort out these pre-paid top up issues they happen every single time I try to top up! It takes multiple attempts for me to just to top up. This really is terrible service!