AG Auto Group They sold us a lemon Vineland New Jersey

We visited AG Auto group in Vineland, NJ two years ago and bought a truck. The truck was 2005 Chevrolet Silverado, since then we've had nothing but problems - blown transmission, rear problems, the windows stopped working a month after we got it, the air bag sensor came on a week after we got it - it is a real life nightmare. We've spend over $12,000 since then and we are $6,000 under water in the loan. Upon contacting the dealership they said that they can't do anything and we're supposed to pay to fix it again ourselves. We bought the truck for $11,000 and he offered to give us $2,500 for it. It has been a nightmare and has caused so much financial hardship for my family. There are other people who have also experienced the same thing with these people. Please help.