Same thing happened to me last year. I warranteed the crappy Cannondale post and while I was waiting for it to came back, I got a Ritchey WCS post and haven't looked back.

Do yourself a favour and get a good one-piece aluminum post (Thomson, Ritchey, etc). It's not THAT much heavier than carbon, and I've noticed no difference in ride quality between the two posts I've had.