Can I get my money back if they fixed my car wrong?

they were suppost to fix my motor from my car because water from the coolant had gone inside the oil and motor making the oil look like chocolate. I got my car back with a loud tapping noise and i dont know if its a valve or a lifter tapping. it wasnt there before. I took it back to them and they said they had no idea what it was and would try to fix it.. a wk later i went to pick up my car and the problem was still there.. they said they cant figure out what the noise is or where its coming from.. it has a one yr warranty, but im tired of leaving the car there with them after they told me they cant figure out the problem and waiting another 7-10days. this was back in oct. they told me that all I needed to do was drive my car on a long trip and the noise will fade and eventually go away becasue of the oil.. 1000 miles later and 4 months later its still there.. should i take it to them and ask for my money back or what should i do..I payed $1,280. for the 2 head gaskets