T-Mobile head honcho John Legeres assuring its BlackBerry-toting subscribers theyve got nothing to worry about despite the companies falling out. But, just in case they are worried (or just want to try other platforms), hes also offering them a $100 credit toward any device. Legere made the announcement in an open letter posted on T-Mos blog, where he also reminded folks they can stay with the carrier and still use BlackBerrys if they bring their own unlocked devices.