Bad Redeem Service

So I visited this McDonald's store in Olifantsfontein and I was there to redeem a voucher I had just received on their Whack-The-Mac special on the App when they told me to redeem and suddenly could not find the order on the system apparently. I was assisted by a lady called Critia and this is not the fist time she tells me that she cannot find the orders on the system. So I'm not sure if maybe the staff is not well trained or aligned on how to find the App specials on the system or I'm just being played. Also I always make use of the App specials and I would hate to resent visiting the store because of the bad service I receive when I come to redeem. So if this can be looked into then we will be just fine.