No ingredients!

At KFC Onverwacht in Lephalale we have had a big problem with availability of ingredients. One time there was no BUNS, the next, no zinger fillets and today again no zinger fillets. I wanted to order a dunked burger but there were no Zinger fillets and then they tell me if I want a regular fillet dunked they will charge me R5 extra. So now they expect me to pay extra because they don't have stock. I feel that this is becoming a problem, every time there is something they don't have. Are they not supposed to have everything on the menu available.