I cant delete my text messages

I have tried everything. I used ibackupbot and deleted all the attachments, but now I just want to delete the actual texts. Everytime I do, the app crashes or freezes and I cant send or recieve texts. Then, when I hard reset my phone all the texts I tried to delete previously have reappeared. Ive tried to let it sit and do its thing but even letting it sit overnight it still doesn't delete even 5 threads. I also changed my settings so that it deletes texts that are over 30 days old and yet I STILL have text threads from over a year ago. I really dont want to have to erase my phone if I can avoid it. Anyone have any ideas?