Very unhappy and disappointed

I am highly and very disappointed with Uber eats. I had a discount of a R100 and it said that the discount app****. When I ordered my food from kfc grassypark and entered in my debit details I saw that they took the full amount and no discount was app****. I then tried to cancel my order and I couldn't. I tried calling the Uber eats hotline and I couldn't get through. I called kfc to cancel and they told me that they cannot cancel the order Uber eats must cancel the order. So why say I have a discount and then once I put in my debit details then it took the full amount of R250. The worst part was that I couldn't cancel the order and the money was already debited. I will never use Uber eats again as they advertise falsely.