Bought a new Impala SS on May 07 with only 113 Miles on the Odometer (miles to deliver to me). While on a trip out of state, I put close to 2000 highway miles on the car . I listed to the radio (XM, FM, CD). Soon a weird fluttering noise developed in the drive side pillar tweeter speaker. Noise would only occur when radio was on and Source had no effect on occurrence. Noise was clearly electronic, not physical and would cease if radio was turned off. Noise would return if radio was immediately turned back on. Only after brief power off, the noise would not return. However the noise occurred several times. Several trips to dealership turned out inconclusive as the problem was a sporadic occurrence. After about the fourth return to the dealership, they finally confirmed the noise and replaced the speaker as a warranty. However problem returned only after I moved out of state less than two weeks later. I took to a local dealer at new location and was met with their doubts. I even used Onstar to contact GM Customer Service and was directed to take to dealer. Finally I recorded the noise on a tape recorder and took to dealership shortly after. They were dumbfounded and simply re-flashed the head unit. Not even a week later, I encountered the problem again and recorded it on tape a second time. They refuse to replace head-unit, stating problem hasn't been identified as the head-unit. I am by no means an electronics expert, but I am savy and know my GMs extremely well. I am certain the head-unit is cause from problem, but dealership refuses to replace. I am extremely dissatisfied with the service. Never been dissatisfied with any other GM I have ever owned (previously owned 8 other GMs).

Any suggestions would greatly be appreciated.