Sign a new Internet service agreement to activate my own gateway? [Edited]

Here's a new angle. I purchased a new Arris gateway and attempted to have it activated on my existing Xfinity Internet account. The chat agent took all the details about the gateway and was ready to activate the device. Then, something strange occurred. The chat agent indicated I had to sign an agreement to have my own gateway activated on my own Internet account. When the agreement arrived it was not an agreement to have my new gateway activated but a new agreement for Internet service. I already have Xfinity Internet service, so I asked the agent what was going on. The chat agent claimed the new Internet agreement included the removal of my old, Xfinity gateway. I have never had to go through this. If I need to sign an agreement to remove the free Xfinity gateway Xfinity should generate a standalone, dedicated agreement just for that purpose. Anything else should be considered suspect.

[Title Edited: "Language"]