Call the resort reservation number and say "make a payment" when you get to the reason for the call. Sometimes you get an automated payment system and sometimes they make you wait for a live person.
I have prepaid over the phone for the hotel only stay. But i now go to front desk before the end of my stay and use Disney gift cards purchased from Target with a Target Red Card to pay against the bill. That way i get a 5% discount on my vacation---even the food and gifts purchased from shops
When the automated payment system works, it’s fast and easy. However lately every time I’ve tried to call to make a payment, it is having “technical difficulties.”
The wait for a live person can be long. It’s so aggravating to have to wait on hold over an hour just to give them your money!