HELP! - Bought a Used Car (Shady Dealer) - Can they make me do this?

So I purchased a used car recently and let me tell you it was a complete headache. I thought I played my cards just right, but the day I went to actually buy the car....the saleman pulled a "my manager said he will not sell the car at that price....it's hot....he must be getting more money for it....bs ...bs...bs" scam .... they boosted the price on me by $600.... I loved the car... and I was in a situation coming from a car accident...so I needed to buy a car as the rental had to be returned the next day....

so I sit down in the finance office and the guy pulls up my credit and gives me a lower credit score then it actually is....saleman tells me it's 699.... finance guy says it.....680.... but the credit scores i pulled from all 3 bureaus were 730/730/729..... they explained that my auto credit score is different blah blah blah.... to make a long story short I signed the deal.... at 9.9% financing....for 72 months.... they totally wore me out.... (not to mention they reported me to live in a different county...i asked about it...and said oh its ok it's the same amount of tax...feel like I got scammed here too).....

so i sign all the paper work.... and the guy gives me a "oh i'm going to have to fight for you to get this rate and get you financed"

they take my 2g downpayment and i take the car with the signed paperwork....

a couple days pass...and the finance guy calls me saying he was unable to finance me.....and that the finance company wants me to put down another 1500 ...boost my interest to 10.99%...and reduce it to a 60 month term....

can they do this...i have the signed contract stating my contract terms.... on the day i bought and took the vehicle home... how can they tell me they want more money....more interest ..and shorter terms...why would they let me take the car if they couldn't get me that??? what in the world is going on and what do I do ? The finance guy has been trying to get me back into the dealership to sign and redo the financing terms and deal....said he wants to do it now...before the interest rates change as they change month to month according to him....what's going on??