What's T-Mobile's Problem?

Dear Tom:
I have a T-Mobile (external link) cell site on my commercial property in Tempe, AZ. The lease called for a 20 foot by 20 foot site or 400 square feet at $700.00 per month. After construction the site ended up being 30 feet by 31.5 feet or 956 sq feet. That's more than double what they agreed to so I've asked for twice as much rent. They've refused, only offering another $150, and now they've even pulled back that offer. They told me, and I quote, "You're not using that property." Help!
I've been through mediation and trying to evict them will cost thousands of dollars. I'm told this is a "footprint" problem. It seems most landlords do not check the size of the site after construction or if they do find out more land was taken there's little or nothing to be done about it. I think they lied about the square footage to get a lower monthly rate. Now what? Know anyone else with a problem like this? I'm thinking about a class action lawsuit.
Dear Reader:
Check the USENET to see if there are other people with the same problem. Go to Google and select "Groups" from their home page. If there are any lawyers who would like to help this person then let me know. Contact me through my contact page.