I submitted a ticket. Customer service sent msg to inbox. I notice msg 4 days later. Couldn’t respond to question. Learned response button removed once ticket is closed.

There are 4 issues:
1) Notification of a new message is not prominent so users notice messages.
2) Even if you close a ticket, users should still be able to respond, reopening the ticket.
3) You should not close tickets when you see the message hasn’t been read.
4) Clearly your people are not thinking through your engagement with users