Inedible food and bad service

Last week I walked into chicken licken at Bosman station to feed my craving just before boarding the Gautrain. I got there and placed my order. Next to me was a gentleman who was enquiring how long his order would be. The staff were busy chatting to each other and ignoring the guy. One of the staff finally turned and started yelling at the customer, telling him to not come buy again if he is not patient. He was given his order which had been ready for a while but because of the chatting they didn't realise that. I got my order and man it was not up to standard. It was oily and soggy. I had to drain the dirty oil by wrapping each peace with the serviette before eating. Again yesterday I went because I love my hot wings. Again it was the same thing. Sometime last year August I complained about the dirty oil they are using, if you put a piece of wing on a serviette, the serviette turns Brown and oily. The clearly are not planning on changing this pattern. The chicken is inedible. Also I have learned that they do not respond to hello Peter complaints cause none of the complaints got response. What exactly should be done to get all the concerns looked at