Pathetic service, dishonest Drivers

I had a Uber ride on the 19th September to Atlantic studio because I had a promo my Ride was 48.00.The driver picked me up and said he needs to go to the garage .He went at 17th Ave Shell, Filled his car washed the windows and after about 10 min we left .Later the afternoon I received a message from my bank the payment returned. I checked I saw the amount was 90 something rand and because I only had 50 in my account it came back .I complained to Uber because that was not my fault and the driver took extra time which caused the payment to be more . The evening I needed to take a uber again which I did but then I paid in cash.The Saturday we needed to use Uber again and we paid cash. Uber then contacted me said they corrected the payment of the Thursday back to 48.00. But none of my other trips were paid because you can't pay cash . I think they need to request the money from those drivers not me ...They took payments .I wasn't informed I can pay cash.They saying have a balance of 128.00,whereby I actually just owe them 48.00. Please assist they have refused to help me on numerous occasions and I have sent it to the ombudsman as well