Very bad experience

I went into a KFC branch with a cyber Monday voucher, there was an error with the advertising on the voucher and i had to wait for one hour to clarify this matter. Within this hour i had a chance to speak to the area manager for Durban - this was a horrifying experience, She was rude and abrupt and a poor reference to professionalism. i had explained the problem to her and she responded with 'then what must she do' - how does an area manager respond to a customer with that sort of attitude. After waiting for an hour i was then told that i cannot use my voucher as it was already entered for the 'error' and cannot be entered again. I have referred this matter to the head office and i had to call them again to find out how far my complaint had gone. Eventually they had contacted me to say that i can come in to the store to receive R36 of my next purchase. My voucher was for 80% off a R200 purchase. But i get offered a R36 discount. This is appalling.