[villagetinker]

Norton appears to randomly send out renewal notices. I have been using their Norton360 product for several years. I went through some similar confusion when I added my mobile phones to the plan. It appears their reps do not understand how all of their products are sold and licensed.
In my case they extended the contract to cover the over payment. If the product you purchased was exactly the same as Comcast offering (*) I would call back ask for a supervisor and a full refund.
* It has been my experience that the version of the software offered by the cable companies does not have all of the capabilites of the full paid version, in which case the partial refund sounds reasonable.

Just my thoughts.