general problems of the 2010 Chevrolet Cobalt

All four rims, especially the front passenger were defective, but dealer is claiming "impact damage". Also, the front two tires have worn either due to defect workmanship or the defective rims. In either case, I have now had to replace both front tires on my new chevy Cobalt purchased March 29, 2010. Gm very uncooperative, closed all cases due to "cannot contact complainant", which is so untrue. I have provided three phone numbers every time I leave my name. They did reopen the rim and the steering issue. Now the tires! what next?.