Customer service

On Saturday 15/09/18 at around 4pm i had been to Mcdonalds Gateway were i had purchased a deal of a sharebox meal from the mcdonalds app. I paid with a R200 for my purchase of R120 the cashier did not have change and she asked if i had a R20 so that she could give me a R100 note i did not have a R20 and she told me to wait aside as she attended to the next customer and that she will sort out my change. I waited i received my meal walking away not realising that i did not receive my change of R80 as i got to the parking to pay for my ticket i realised that i havent received my change. i went back to the store looking for the cashier and could not find her i then spoke to a manageress by the name of Thandeka who had told me that she would sort this issue on monday as she can only view footage on camera on Monday and she would call me back its now Wednesday and no feedback. Its not right that i have to run around when it is convenient for you guys to resolve this im not being reimbursed on my fuel . Id like someone to resolve this issue and contact me