KFC
Overcharged on goods as advertised

After my very bad customer service experience a few months ago, we decided to give it another chance, much to my regret.
I stopped at the KFC for an AM Riser with cappucino, advertised on the billboard as R24.90. I paid the bill which also included other items, and realised that I had been charged R16.90 for the food AND R14.90 for the coffee, a total of R31.80. I confronted the staff, who told me that "the special was over". As I was late I could not stay and make a complaint at the store, but I feel this is unacceptable.
I have already had a previous complaint at this store and had to settle for a meaningless letter of apology- obviously nothing had been done to improve standards at the store which seem to originate in the way the staff is trained, the negligence of not removing billboards when deals are finished, and the none informing of customers that the deal has been changed.
As of now, KFC has R7.00 from me- I wonder how many others did not een notice that they have been overcharged.
This time an insincere letter of apology is not good enough, please let the store in question get their act together.