Our testing has revealed that Apple has fixed the bugs in iOS7. Please update your phone for reliable Mass Text Message app performance. Open the Settings app -> General -> Software Update.
If you are still using iOS6, I recommend waiting a few more days to ensure all of the bugs have been fixed.
Please reply to this blog post and provide feedback about your experience with iOS7.1
Thank you for your patience. We are thankful that Apple has finally addressed these issues.