Robed By Uber Eats!!!eats

I have just got home today and decided to purchase bread online as uber eats has a special for grocery stores at 50% off when you spend R175,after doing my shopping my total showed 50% off I then went onto check out and this is where the problem comes in not only was money taken out of my account without authorization but I was also charged the full amount, now if I was able to confirm payment on my app I would have seen I was overcharged and canceled. No way to contact them beside an agent of no help, or cancel the order while speaking to an agent they tell me they cannot help n say I should contact support of which no way of contacting them via the app then the agent decides to end the chat without my issue being sorted, absolutely unprofessional I've never had a care of Robert with MR D Delivery!!