I agree with you Sara. However, I wonder if there is another factor here.

Has Comcast arranged with your HOA or your town to have permission to do things like this? While being able to dig in your yard sounds like a classic example of an easement (they may have arranged with the builder to have permission to run lines), I cannot believe that this would extend to physically attaching something to your house. Yet, I can see some HOAs feeling like they have the right to sell rights to a company like Comcast because someone in your HOA agreement, it says that they can do that.

So, if you live in a HOA neighborhood, read your bylaws. If they are the ones that gave permission for this, then you need to protest to the HOA board.

If not, then see Redhead's advice, below. It's good advise.