Infinity AM Radio

I have a 2004 XG350L that I purchased in October 2003 and it has 8,400 miles on it today.

I absolutely love this car....except for the radio. My AM radio has a god-awful whine in the background. To the point where you cannot hear the words. I have had it into the shop more times than I can count. I still is not working.

I drove a used one on their lot yesterday that was identical to the one I have and the radio was fine.

The service technicians keep telling me that is just the way it is. Well it isn't. Is anyone else having these problems with the Infinity Sound System, AM radio?

Thanks,
Perplexed