I agree with mountaindog on this, since the problems began while the camera was under warranty and were never resolved to your satisfaction, these problems should still be covered. I would suggest contacting the manufacturer directly and submitting copies of all your paperwork showing where you submitted the camera for repairs under warranty. Ace's suggestion might work, but you have to hope that no one will think to match the serial numbers on the box with what is on the camera.

FWIW, I went through a similar experience with a Sony TV and was able to finally get a replacement almost a year after the original warranty had expired; I simply showed the documentation where the set kept getting sent back in for the same problem.