Nando's online faulty payment

On the 11th Dec I ordered a full chicken + two sided on the Nando's online portal using a R125 voucher and card payment of R119. When the delivery guy arrived at the gate he refused to give the order saying I didn't pay the difference.

I had to go to the physical Nando's is Broadacres where a rude manager told me that I didn't pay and I cannot get my order. She was even brave enough to say this far 5 customers had experienced the same issue with part payment on their online portal yet Nando's hasn't taken steps to fix it. I had to pay again in store to get my food and was promised my another male manager that they will launch an investigation with their IT department on why l was charged yet the system still required a payment. I still haven't received a call from the store nor a manager yet my bank has authorised two payments. I feel ill-treated for Nando's own online fault that I have to be charged twice. I need my refund.

The rude female manager's name is Makwena and the other male manager's name is Sayi.