How can i be affected if i want to sue the dealer where i bought my car???

i just bought a cadillac cts 2004 and the 1st weeks after i bought it it game me problems with the brakes. i took it to the dealer and they said they fixed it but i kept having the same problems. 2 weeks after i bought the car it left me stranded in the market and i had to get a tow truck to take it home. i took it to the dealer and they said they fixed it again but i continued having problems with it. I took it back the next day after they said they had fixed it and it turned out that the transmission was mest up. they told me it was going to take 4 weeks to fix so i could choose another car instead i chose another 2004 cts but they wanted me to pay more money because that cts was more expensive. i want to cancel the contract and everything now, but i do not kow if this will affect my credit or what outcome i will get out of this it has been 3 weeks since i bought the car HELP!!!