need help on moms car. paying through toyota financial?

the car isnt a toyota its a audi mom took out, not from a dealership but from a car lot. they were able to get my mom a loan from toyota financial. this was 2 years ago. she need 3 years to pay it off but the things is that she might not be able to make a payment this month for emergency.

how much will she get charged on that bill extra? and cuz of the late payment she will have to do, will that raise the interest rate? shes paying to much for the car $657.00 per month (well i think shes paying to much) but if she doesnt want it no more, what can she do about that? shes already has a good house and other cars and she dont care if her credit score gets screwed up, can she return the vehicle? but mainly how much will the bill be for that months missed payment?