I changed my room reservation yesterday. Booked package directly through AAA, wanted to add dining.
The deposit was 200.00. You have 15 days to pay, but I went ahead and put on cc. The remainder must be paid in full 45 days prior to arrival. You can pay this to AAA, doesn't have to be to WDW Travel. She also told me that you can make payments anytime you want as long as paid in full within the 45 days.