Loupito....
I just bought KP-SHO from Origin a few days ago and the serial number didn't work. I used the Live Chat function in the Help section and, after more than an hour wait (usually not that bad but I'm guessing that with the big sale at Origin, there were a LOT of issues), I was able to get the customer service person to give me a registration code that was valid.
So, while it might take a bit, they do keep you updated as to approx. how much time you'll have to wait (i.e., 10 to 15 minutes, 45 to 50 minutes, etc.). You can probably step away from the computer if you need to if there is more than a 5 min wait. There's a thread on this issue so those guys are aware of the problem so don't worry that it might be a problem.... :)