My father’s care manager went to America for 11 da

My father’s care manager went to America for 11 days to see her daughter who is studying abroad in San Diego.
Because I haven’t recieved a phone call about my father’s problem , I have been relaxing for 11 days.
I didn’t want to worry about him.
Last Tuesday a care manager called me , “ Your father got a taxi with a wrong coupon ticket. He didn’t pay the taxi fare. He is going to pay it at next time if he has the chance to take the same taxi: The taxi deliver is really angry.”
My father usually uses a Kaigo taxi that provides a wheelchair and a stretcher . He made a mistake and gave him a different company’s coupon.
The Kaigo taxi coupon is provided by the Tokai city hall.
A care manger went to the Kaigo taxi driver’s office to exchange the coupon. My father didn’t apologize for his mistake.
He has a taxi ticket and will pay it later. The taxi bill is automatically withdrawn from his savings account. He can take a taxi without using cash. It is convenient for him but, it is dangerous for him not to remember his payment.
My father is going to buy a Mobility scooter that has a seat ,three to five wheels ,and is battery powered. It runs about 6 km/h.
It costs 550000 yen. His doctor will not give his approbal for my father to drive it because my father doesn’t have enough ability to make good judgements.
If he hits children , what should I do?
I he cause an accident , what should I do?
There are many problems. He has not listened what I have said . I am looking for Mobility scooter’s insurance.
He is always my trouble maker.