Fly eggs and then attitiude when you complain

I bought a beef burger special yesterday afternoon at vat cake city Valhalla around 18:15 for my pregnant daughter who is visiting and that is what she craved. got home just to find the patty full of fly eggs and this after I had to wait so long. When I called them just before 19:00 to complaint no one answered. I called now to raise my concern and the reply was, if you do not have a slip we cant help you, yet the manager took my slip when I was complaining after 40 min because I have not received my order as yet. Really really bad service and client service... What a disappointment ..