Step 1. Ring your finance company, explain the issue and that its basically f*cked within hours of purchasing it. Get the facts, find out what they suggest you do next and what (if anything) they would plan on doing next. Don't proceed with anything just yet.
Step 2. Ring the dealership you bought it from, explain to them you either A. Want your money back or B. The car to be completely fixed 100%.
Whichever decision you go with, I'd suggest you get EVERYTHING in writing, confirm EVERY step with the finance company. That way if sh*t hits the fan you have some come back and an agreement from all parties. Your number 1 priority needs to be keeping the finance people on your side, since if it all goes belly up, it'll likely be them that saves your arse.