Horrible customer service and overcharging clients

I have very disappointed with the service I am getting from Uber eats . I am a Sanlam wealth client and mid October 2025, they allocated a Sanlam wealth bonus on my account which gives me 20% off discount on rides and orders. I have been a loyal client to uber eats for so many years and I always order via them for convivence. Since the discount has been app**** , I cannot place an order , it always says something went wrong , on the 23rd of October I then logged a complaint and advised Uber of the issue , they did'nt really help. Everytime I place an order , I see my discount but it will never go through unless the discount is removed . I have then asked Uber to kindly please refund me all my 20% discount in Monetary value as I have been overcharged , I have notified them about these incidents and also sent them screenhots but I am not getting assistance. Now they are asking me to provide them with order numbers, which they are suppose to have as I ordered through them and they have all the data on their end. When you send them messages , they ignore some of the things mentioned and only answer to what is relevant to them. I earned my discounts and they are suppose to help me save where I can. I now demand a refund for all the orders placed since 23/10/2025 till today 07/11/2025. I would also like to know what is the solution for discounts to pull through as even today they don't , I did try reinstalling app but still getting the same error.