Disappointing Mcdonalds Chris Hani Road experience and quality

We went to Mcdonalds in Chris Hani Road drive thru Durban. We purchased the large bbq meal that was on offer on the Mcdonalds app. At the drive thru we were told to just drive on to the payment window as we were redeeming the offer from the app. We get to the payment window and encounter a whole lot of confusion. My husband and I both got the app and wanted to redeem the offer from both our phones in total 2 meals. We were told that it had to be seperate transactions and we needed to swipe our card twice. The meal was 39.90 each, so the manager was assisting the teller and first swiped my card for R103,and thereafter wanted to swipe it for the second time for the second meal. So we questioned her as it was supposed to be R39. 90 per meal and it turned out we actually paid for someone elses order. She then returned the money in cash minus our order value with no apology. At the collection window we received someone else's order, mistake number 2and then were told to wait in the parking lot and will receive our order shortly which defeats the purpose of a drive thru. Our slips were taken and never returned hence i could not rate the service on the app as it needed the details of the slip. On receiving our meal we encountered yet another disappointment, we found the burger totally smashed and wrapped up, it was almost as flat as a pancake, the chips were all out of the box in the paper bag. It was such a terrible experience and poor service as well as quality. Will never visit the chris hani McDonald's again. The manager i assume that was assisting the teller was not versed as well in how the app offers work, so poor service...