Nando's store manager fails to provide feedback

I had called Nando's Crescent to order food for pick up. when I got there, my food was ready reflecting my name on the receipt on the brown bag with my food. the lady asked me to go to tellers to pay which I did after waiting in the line, after paying and going to pick my food up I ask the staff member are you sure this is my order and she responded "100%" then I decided to look inside my bag to ensure all that I have ordered corresponds to only find out that it was not my order and that she had swapped my order to the Mr Delivery Guy. This was beyond inconvenient considering the reason for me calling in to order was so that I can walk in pay and walk out. I requested the complaints line then and there however they gave me the store managers(SLI ) number who was not on duty. she then instructed the staff to give me a full refund which found another problem. my meal was R118 however they swiped my card for R131 which aggravated the situation further not to mention that they only gave me R118 and argued about the balance of the remainder as they can not over ride the till or some internal problem. I eventually got the difference between the two amounts. Sli promised to call me back the next day at 4pm to advise on a way forward so I provided the opportunity to rectify the error. I am still waiting to get a call from your store manager Sli, I have tried calling her 6times with no answer nor interest in this situation. I have my call log to prove this, I also have both slips as proof(the card receipt and the nando's receipt).