Mistreatment by driver

I requested a ride from Bolt on Friday from my house to the hospital and the driver came to pick me up with another client in his car and told he's dropping him off nearby. The driver drove about 5km's to drop off this other guy and then only drove to my destination. When i got to my destination i noticed that he had already started my ride on his way to drop off the other guy and as a result i was overcharged and when i confronted him he said there's nothing he can do it's already charged on my card. I was left stranded in hospital with not enough money to go back home because of that!! I would like my money back, im unemployed and have a sick child in hospital which i have to visit everyday so please!!!!