Incorrect balance

On the 25/07/2025 I bought from fashion fusion using the PayFlex I bought things for R526.48 which is my credit limit was R1666.66. As I have agreed to pay for 3 months however I made the first payment which is my second payment it was on the 25 August the amount of R175.50 however when I was opening the App on the 2025/08/15 trying to make a payment before the due date they say I am owing them the amount of R-467.97 I have no credit and I tried contacting them the is no response.