What a bunch of con artists.   I had trouble with a credit card.   So I informed them about it and paid a couple of payments by mail.  After I made payments they cancelled my account so they and placed me in collections. Then mailed out box for equipment because they profit off of collecting a 200 dollar cancellation fee that they cancelled; not me.   And then they say that I need need to pay 514 to pay off old account.  That I need new equipment for a new account.  
I wonder how many people out there that has been scammed.

Is the wireless adapter a box? Thanks for the information.  

Here is what I use:

Having linking issues, anyway fwiw on Amazon or elsewhere perhaps the: Alfa AWUS036NHV

Mind you, if I couldn't find an Xfinity hotspot with this there are even more powerful antennas I could try to mount on the outside of the house, rather than just putting by a window. But that would be pricey and involve finding mounting hardware etc.

Of course this sort of thing only works if you have an Xfinity wireless hotspot in the area. If you have a wireless device, check if it shows up or not.

If you have Windows for example, you click on the bars to call up your wireless hotspots:

Example

Then you click the xfinity wireless hotspot, and sign up.

Xfinity hotspot and it gives you access to a signup page, where you can try a free hour once a week, or pay for a day, a week, or a month at a time Internet.

Just a note -- their paid plan only works on one device and wireless adapter at a time directly, it's tied to the one device.

Well, anyway fwiw, this is what I have so far found in my quest for the cheapest Internet service I could find.