This happened to me in Dubai. I was at the souk and traffic was really heavy. I contacted Uber and they credited my account for a future ride, but this was no good, because the credit was in AED, and the credit wasn't even received until after I got back to the States. So I disputed the charge with AMEX because I have no patience for run-around and shenanigans and didn't want to go back and forth with Uber, and AMEX quickly reversed the charge on my credit card. Uber's policy is that if a driver waits for more than five minutes the customer is charged a cancellation fee, but this is bogus if the driver doesn't show up, and doesn't even call if he's having trouble finding you.