CarHop UAC overpriced non-working van after a week Vallejo, California

I bought the vehicle for my wife  for her birthday on 8/11/2012. When we test drove it ran fine and a few days later the van wouldn't start and after trying  it a few times it started. A few days later the Check Engine Light cam on so, my wife took it to the AAMCO to see what the problem was and AAMCO told her there was an EVAP (emissions) leak and would charge us $120 to check it out completely. She then took it to CarHop/UAC; the place where I bought the car and the mechanic said it was the gas cap and reset the Check Engine Light and sent her on her way.

The very next day my wife went to a meeting and after the meeting when she was on her way home she tried to start the van and it wouldn't start so, after sitting for about 20 minutes she than tried it again and it started and it got her home. The contract says I had three days to return the van in the same condition but, I don't want a vehicle that I can't drive but have to pay for. I either want them to fix it correctly or let me out of the contract. 

I don't have money like that to put into the van to make it run right. The cash price for the van was 10,395 which was the amount they listed on the DMV papers and they financed it to me for 11,479.15 with the total price being 15,174.99; which again wasn't the same price listed on the DMV papers. The Kelly Blue Book is only at MAX 3,360 for excellent and 2,285 at the fair value. Although my credit isn't that grand, I think I could've went to a real dealership and got a working newer modle vehicle.