Did you activate the 2nd line for the 2nd phone?
I would try calling the rebate support number directly. I had the same thing happen when they tried transferring me. Calling direct worked every time and they're much more helpful. Do the following to get through to a live agent:
Press 1 for English.
Press 2 for Terms & Conditions
Press 2 for General Instructions
Press 1 for Additional Assistance.
Hope you get it sorted out.