1. You can find the physical address for RIM in Waterloo, ON, at the RIM website, I recall seeing it the other day, while getting my Christmas card list in order
I also feel certain you won't get much satisfaction from RIM, directly.
There's really only three reasons Sprint wouldn't replace or help you out: Moisture damage, physical damge, or the CSR is a nutjob.
Meanwhile, for $15 you can replace the trackball yourself, although it would likely void the warranty.
So... can you explain why is not working about the trackball, and what/why Sprint said they would not replace the device?