Whats going on?!

This is literally one of the first apps I downloaded when I got my iPad years ago. Now everybody in my family and extended family have it and love(d) it. For us about a month ago, the notification stopped working, messages can take days to appear. Please please please fix whatever issue this is!!! ***Ill change to a 5 rating when it is working properly again.***

T.Ferrari21 about Textie Messaging - Beautiful free text chat unlimited (SMS), v1.2.6