Over charged me

This is not the first time uber is doing this to me. When I called for the uber yesterday it showed 30 rand. I took a trip a few times from the same location before and it was usually 29/30 rand all at similar times. UBER Charged me 50.00. This is not the first time you are doing this to me where you charge more than what you put on the app. I didn't make a mess so cant be a cleaning fee nor is my account in arrears ive never cancelled any trips recently. You do this all the time to me. And I have proof that you charged me 50 rand and not 30. I can imagine how you're doing this to many other people by over charging us.