Incorrect charge

25 of march I ordered a pizza online with extra feta at debonairs umlazi mega city. A manager named Mpume called to tell me that they dont have feta and they will remove it from my order. When the pizza arrived they had charged me for double feta. I called her and she advised it will be credited back on my next order. When I called now to order again and reminded them of the previous incident they say there is nothing they can do about it. I'm furious