Extremely disappointed in Uber eats

Good day,

Friday morning I used my voucher I received from dstv of R75.00 towards my next meal. I then added the promo code to my uber eats app and I received and email stating my voucher has been added to my account. I go on and purchase my meal and had to pay in R36.00 difference which I selected cash. When the delivery guy delivered my food,he said I need to pay R111.00. I explained I used my voucher and gave him the R40.00 he said I can contact uber eats.

I then emailed them screenshots of the promo code,the email showing its been added and the notification showing I need to pay in R71.00.

I finally get a reply today and the consultant says there was no promo code added then I sent a screenshot showing the email I received from uber eats showing my voucher was added and my order was made 10 minutes later then the consultant says the promo code is not valid. so how did I know the difference I needed to add in if the promo code was not added and how is it not valid when I have proof in my email that it was loaded?

This is poor,poor service and I'm very disappointed in them because I always use their services. I will be sure to let my family and friends know about this,especially with vouchers because according to the consultant they can't help me yet I have all the proof!!!