How to extend a public hotspot with Airport Extreme

There is an Xfinitywifi hotspot near my house that I would like to boost the signal with my AirPort Extreme. My current setup is too slow, I'm using a 2008 MacBook Pro, logged into the comcast xfinity wifi, and shared the internet through Ethernet to my AirPort Extreme. It works perfect, but the internet sharing in Mac OS X is very slow (as expected).

I also have an Apple TV that can't connect directly to the xfinity hotspot because you have to log in, so I would like all my devices to be on the same network/router.

What can I do to make this work better?

imho - pay for your own internet access instead of hijacking it from what is designed for comcast subscribers and visitors to the business providing the service at that location.

Stealing cable/internet access is a prosecutable offense in most states.

I pay for access to Comcast's Xfinity hotspots. This is my last resort until somebody from comcast comes in two weeks. I've spent a total of 5 hours over the past 3 days trying to get my internet activated on my modem. I've added multiple services, and every time I call they say they can't find the service added to my account.

The least they can do is let me use the xfinity hotspot near my house that I pay for. imho.