AT&T tethering letter... How to respond?

Hey,

I have been an iPhone user since day 1... Complete with the grandfathered unlimited plan.

There is no shortage of disdain for how at&t is treating unlimited plan users... Even those who use miwi jail broken to tether on occasion.

I got a letter in the mail saying that they will change my contract unless I stop using miwi and call them or something to that effect.

This has happened to a never of users... How do you suggest I respond?

This thread is an example of what I am talking about....

http://stopthecap.com/2011/06/07/att-will-start-auto-enrolling-unauthorized-tetherers-in-45-tether-plan-june-10th/

Advice?

Thanks.

r