Why Can't The Channel Guide Remember My Zip Code?

I have a problem with the channel guide.  Every time I go to see what's coming up on TV, I automatically get the channel guide for Philadelphia.  I've put my own zip code in and SAVED hundreds of times by now, but the next time I go to use it, it will not be my channel guide.  It will be the default guide for Philadelphia.

This is a pretty simple procedure that I would think shouldn't be an issue.  But, it is.  And it's become more than a minor annoyance.  I can't have much confidence in a service provider that can't handle basic issues such as this.

I'm looking into a new service provider.  I've already contacted one who assures me that their programming channel can handle the input of my zip code.