group text is not working with ios7 upgrade

Group messaging is no longer work with ios7. Have tried some suggestions in other threads but none work including resetting "all settings", rebooting the phone, trying different group text apps, etc. I have various groups of contacts for sms - with the number of contacts ranging from 4 to 100. In settings> messages> there is no option to turn on group text. Any suggestions? Smaller groups of contacts seem to work ok - only receive individual replies which are not in the group. Larger groups cause the app to crash.