A ghost agency that doesn't care about its tenants...

A ghost agency that doesn't care about its tenants. I haven't had any heating for a month and it's up to the owner (so they) to take care of it. Their answering machine is full and can no longer take messages. By email, they kill and do not respond. And by mail with acknowledgment of receipt ... The mail comes back to me refused.
Flee like the plague Ammonitia! Even for moving we do not know how to do if they refuse the mail of our notice by registered mail!