Refund from Uber eats

I used uber eats on the 31st of Dec in Cape Town N1 city for Mcdonald my amount was R96.90 in total for my food and when Fabrice the uber driver delivered he charged me and I gave him R100 and he didn't give my change. The R96.90 was already charged in my card. I complained that I was charged twice and uber eats said they will refund me R70.70 which they did on the 2nd of Jan but again took it back R70.70 and never refunded me again. It puzzles me how they can charge me twice and return a small amount and take it again. Am not happy with uber eats.