False advertising

This is with regard to the Nando's birthday special meal. I went to Nando's Chillilane on the 27/09/2017 to buy food. When i got there they still had the birthday speacial meal sign up and it did not state sold out for today. I went in with the impression that the meal is still available because usually when its sold out, they put up the sign. When i got to the till i was advised it has been sold out for more than an hour. I asked why did they not turn the sign around the cashier told me she did not have time to do that. I was appauled by her explanation because she is not the only staff member at the store and she was aware that the special has been sold for close to an hour and 30min why did she not take the initiative to ask another staff member to quickly turn it around so that customers are aware and not come in with the impression that it is still available. None of the staff members where helpful instead they told me and my friend that they are too busy and dont have the time to go turn signs around. I am very unhappy with the service i recieved and how rude the staff is. It is unacceptable for them to give customers false advertising and then they refuse to take ownership for it, all they could say was call the customer care line if you want to complain.