2 landlines with no dial tone, one is fixed and one is not!

No service on both landlines (old copper lines) since Jan 6.  Created tickets for both. Today one of the lines is fixed from outside of home without the tech even reaching our interface box. He just called on the said landline to make sure it was ok. The other landline with the same problem, no dial tone, however, still not working. My elderly disabled mother relies on this line and she's been without service for a month now. ATT tech was supposed to come on the 28th but never showed.  How is that they can fix one of the 2lines from the outside but not the other one?