2007 Impala XM radio feature?

My new 2007 Impala has a factory installed XM radio. While this isn't a regular feature for the 2007 Impala LT, my understanding is that it only needed a software activation key to enable XM and let me to register the radio. I have gone to two dealers to attempt to get this enabled. The 1st who delivered this company car told me all I had to do was tune to channel one to get the radio ID. I clarified that the XM feature was no enabled. After going to each department by phone, they said they could get back to me. Nothing still. I stopped at a local Chevy dealer and made the same investigation. They sent me to the accessories man who told me I needed a module. I bought the module, took it home and discovered it was an Ipod control dock. Nice but not what I wanted. The information state the dealer must use the Tech two program tool to enable the "digital radio reciever". I called the dealer and nobody looks to have done this before. Does anybody know how this should work?

Does your car have an XM antenna? Have you seen the back of the radio to see if it has a connection for XM? it'll if the XM is fitted to the unit. it is a little square connector with a round pin.

By the way, I installed the 1st XM car system in Los Angeles, so possibly, the United States.

I have been a professional mobile electronics installer for 25 years.