Update....
I decided to try my luck one more time. After being on hold for 20 minutes, I got through to someone and got cut off mid-conversation. After another 20 minutes on hold I spoke with someone else. The problem with calling spring after normal business hours is that all the calls get routed to India and the reps repeat what I say ten times after asking me the same questions over and over again. It's enough to drive a sane person over the edge.
Anyway, after getting the run-around for 20 minutes the rep told me to speak with someone in the rebates department and she would note on my account that I should be credited for the rebate. However, the rebate department was closed, so she gave me the phone number to call them in the morning. Since I also wanted to try the Kellog's $75 rebate I asked her to email or mail me a copy of the invoice for the phone. (I purchased the phone online and usually print these out at work but I wasn't sure if I did, so it didn't hurt to ask.) I guess at this point, since the call was going on close to half an hour after I had been put on hold several times she just relented and offered to give me $100 credit for the rebate. Total price now down to $299 for the Mogul.
Persistence (plus a bit of luck) pays off.
Now Kellog's.....