Pending Payment

I have made arrangement to pay my account on the 18th of every month for 3 months R800 monthly because my account is in arrears. I have paid the account using mobile payment to date that amount is still on pending payment & it has been debited on the 16/10/20

4 days ago I got a call from Durban regarding the payment, I did mention I used USSD to pay& the consultant said they were expecting the money to be paid directly at Mr Price shops. She asked I send proof of payment which I did immediately after the call. Haven't got response from them since. I am worried my arrears will go up & an arrangement was made& I was told they will lock the account for me not have anymore arrears.