Upgrade Disaster - AT&T Not Helping

I work as the onsite manager of an HOA in California, and we had our copper lines switched out for AT&T's Internet Air 5G Gateway. This was done on 5/24/24, in the in midst of installing the equipment, the AT&T tech changed over two of our landlines to cellular lines. Those landlines happened to be connected to our fire monitoring system through ADT and the next day an alarm began sounding off in our telephone room because the fire monitoring system is unable to communicate with ADT when sending a signal. When we asked AT&T about this, they said that the numbers had to be changed temporarily for them to be ported correctly. But then several days went by with the alarm activating every hour and me, subsequently, having to leave my office to silence the alarm. 
Last week on 5/30/24, I sent an email to the project lead at AT&T to let him know that ADT was scheduled for Monday, 6/3/24. It was the AT&T technician that specifically requested that the fire monitoring company be scheduled so that they can work together. When Monday came around, what do I come to find out? That my email was ignored, and they cannot send a technician. But hey, at least they let me talk to the Engineering Department. The ADT tech reported that he was able to create a dial tone, indicating that this is an AT&T issue. 
Also to note, it costs my property nearly $1500 for every visit by ADT. So not only is AT&T slacking in providing even a modicum of service, but they are also costing my homeowners money. 

And here we are: THREE WEEKS since AT&T did this upgrade, and they are not showing any urgency in getting this fixed. I have homeowners who can hear this alarm sounding in the middle of the night over the weekends, but AT&T doesn't seem to care. The entire installation team refuses to answer back my emails, so I had to call Support, who sends me to the wrong department after an hour on hold.
To say I am disappointed would be an understatement. Never have I seen such incompetence and lack of urgency from a company that supposedly strives to make a name for themselves.