Shady business practices.

I recently did a private sale threw bank and its mandatory to use them. After taking delivery from vehicle the next day the car leaks oil everyday. I enquired about how the vehicle passed roadworthy I was told that they only spend 20 mins inspecting a car and could not be kept liable as they don't spend enough time on inspected car. I thought they give client and the banks peace of mind as the bank is also buying and asset. Made enquiries at other roadworthy centers and they advise me that it should have not passed for roadworthy.