Are you sure you bought the right upgrade? There was a CS2/CS to CS5.5 specific upgrade and you did need to be upgrading from another suite.
If you absolutely bought the right upgrade then you will indeed need to contact Adobe for assistance.
I did lots of research to make sure I bought the absolute correct upgrade. It took me forever to find it and now I cannot get it to install. Can't get the chat button to show up so now I've got to troubleshoot that, I guess, to get help. So, I have to wait until Monday to talk to someone???