I had much the same experience as steve258 time-wise with a WD laptop drive. About 3 weeks.
I got mail to say they had got it, then it seems to get lost for a bit when they send it to they send it to be repaired / examined.
The package will be forwarded to the service center for processing, upon receipt at the service center you will receive an email indicate that your drive(s) is being processed.
I wasn't very impressed by the way it was packaged when sent it back to me.
Nice box with 2 pieces of foam for it to fit between, and they had put it on top of the foam against the box itself!
It wasn't damaged though.
Drive originaly failed as it's in a laptop that runs soo hot its untrue. (HP with celeron at 2700)
It's on it's 3rd drive now and I don't expect the new one to last longer than a year if the others are anything to go by.