You do have service books. You can re-send them from your my.t-mobile.com account or call customer service (611) and ask them to resend them. Often message related issues center on service books.
if you're resetting 10x/day you have a defective device or a terribly bad OS installation. wipe and re-install OS. if that fails, pull the warranty card.
8300 Curve: viigo, gmail, google maps, way too many emails/day