Wrong Order & Wrong Slip

I purchased two sets of meals on the 31st January, one was a chicken foldover medium meal and a single McFeast burger. <br> <br> This is what happened:<br> * I received the correct meal for the F/over<br> *She give me the incorrect order for the burger, they gave me McRoyal burger, I wasn't even aware that time.<br> * I then requested for the slips for my orders, only to find out that lady who was helping me decided to give me the slip for the f/over on the till she was using and she has to use another till, of which I didn't do the payment on to get me the Mc Feast slip.<br> When I got to work there is a surprise, I have a Mc royal burger with a Mc feast Slip, HOW IS THAT POSSIBLE?