The bank should have the original file, duplicate keys of the car. And registration book if the owner has not claimed it yet.
Payment receipts dont mean anything.
The documents you need are
Original file of the car (sales invoice, registration documentation)
Registration book or card as per the province you are buying from
A NOC issued from the bank, on the owners name stating that all payment are cleared and the car can be transferred.
Such a car would be double transfered usually. Might cost you 2000-3000 extra to transfer such a car.