@emmazz
Noone ask your URL, I am very disappointed that you are lazy to even completely report issue and then complain how bad is support:
- how is possible to get issue (what steps)
- what kind of listings were not marked as duplicates
- what are settings of duplicate check in plugin settings
- list some example listings (title, desc, user email, ...)
I have no idea what is problem there to describe problem.
Or your URL describe it?