Downtown auto sales Worst dealership! Lied about fixing an o2 sensor before purchase! Manchester New Hampshire

I recently purchased a vehical from them. The day I test drove the car I let them know the check engine light was on. They told me it was the o2 sensor and that they would have it fixed before I signed the papers. 

 The day I came to pick up the car the light was still on and I was told that I had to put "a lot" of miles on it for it to reset itself. I drove 500 mile then called and they said drive more. So after another 500 miles they had me drive 1 hour and 15 min. From my house to the dealership, I was told they were going to fix the issue and I get there and he tried to reset my light again. So that was a waste of A trip. 

 I tried contacting them a week later and no response I tried daily! Then finally I hear from them they tell me to bring it down to have it fixed. So I leave work early to bring it down we agreed on 4:00, I get there and they are closed it's only 3:30! When I spoke to them again I was asked why I didn't leave the keys in the car and just leave it! Hmmm because it's manChester and my car now not the dealerships.... Sorry I don't need it stolen! 

so after this I gave up on them contacted my mechanic and the attorney generals office. My mechanic put in the o2 sensor and the light went right out! He told me that it had never been changed they just lied to me. Dealerships like this need to face the law! This shouldn't happen to anyone!