Be warned: These people are NOT affiliated with the United States Patent and Trademark Office (uspto.gov).
Their only work is to renew your trademark for you and charge you a whole lot more than if you did it yourself. According to the current fee schedule for trademarks through uspto.gov (the official government agency that handles patents and trademarks), an application for renewal should cost $400 (as of the date of this posting). The letter I received from the Patent & Trademark Agency LLC shows they will renew my trademark for $985, so they're pocketing $585.
Their address is 477 Madison Avenue, 6th Floor, New York City, NY 10022. Keep an eye out.
Here's a link I found while researching these people:
My notification letter looked identical to the one in the link above (but with my own information, of course).