Could not have said it better myself.
I don't trust the amex credit cards anymore and about 50-75% trust my amex charge card.
Sorry to hear it, OP.
Sheesh - maybe we should start calling 'em AmAxe!!!
You can join my club now, the F*amex club - and I am sorry to say there is a snowball's chance that you'll get them to recon that decrease. You have joined the masses of good paying customers who they have spit on, and I have been reporting them to anyone who will listen since early 2008.
Don't be too surprised if they take even more of your line away. Sorry this happened to you.
To any of you out there who are still singing the praises of this company, make sure to DUCK! often as this is proof that it's not just those of us who carry a balance who are getting hit.