RCS not responding to account

I returned a pair of shoes to Brooklyn Edgars on 13 August 2020 which was the only merchandise I had purchased on the account since I paid off the account at the beginning of August 2020. I have a final credit note (******9561 15:07:46) from Edgars showing a positive balance of R22.32 on my account on 13 August 2020. I received communication in the week before 7 September indicating that I still owe the full amount for the shoes with no record of the successful return. I have subsequently spoken to RCS during the week of 7 September 2020 and was told that the issue will be investigated. After this interaction I received an SMS on 12 September showing that I still owe the amount, indicating that the conversation around 7 September was completely ignored. I phones RCS on 14 September again requesting feedback on this issue with now response. I cannot understand why I am hounded about money I do not owe.