Help getting a car

Our car from a finance company was sold to us with unknown faults to us and has been in and out of the garage costing us more money than we have only to be told by the garage it has a blown gasket. This car is vital for my family as my stepson is going through treatment for leukemia so having the car to get to school, hospital and work is now too much of a struggle. The worry of life for us is becoming unbearable with health and my job on the line. We could really do with the help which would be greatly appreciated.