wrongfully charged for cancellation fee

I requested uber at 15;38 and a uberx driver accepted and the ETA time said 5 minutes and it was just down the road where he excepted. so i waited around 3 min i still didn't see the uber driver move. so i sent him a message asking if he is moving because my app freezes alot since the update i did a couple days ago. and i didn't got response from him i waited after 10 min after being excepted and his location didn't change. so i gave up and decided to walk to work before i got fired considering i was already running late due to this situation.

I get to work and check my emails and i get a cancellation fee of R25.00 how does that work when the uber driver wasn't moving and took 20 min to get to me ( according to the invoice) from a 5 min ETA. I have been using uber everyday since i got it. Please help.