Unauthorised Uber transaction

In August i requested a ride and it was accepted, however the driver cancelled and the ride was paid eitherway and i was charged additional charge of cancelation even though i was not the one who cancelled the ride. I queried for my refund and sent emails message on their app nothing happened. Today i see a transaction that failed in my account due to insufficient funds. I am upset and really annoyed because i fail to understand why is such happening. I had to uninstall the app