How to get past tier 1 tech support for a already diagnosed issue ?

I have had fiber service since April and it has been rock solid until my neighbor starting building a fence.  

Line was cut of course but the ATT support person I go ahold of didn't want to hear my ideas on what was wrong.  They did not seem to be able to 

determine if it was a problem only with my service or if my neighbors had issues as well.   

So I get the scheduled appointment the next day , 4 hour window, miss work etc. 

The guy shows up and agrees - yea main line cut - everyone hooked up to this box is out.  I can't help so I'll call in re-enforcements to fix main line.

That evening ATT workers are out till 11:00pm working on it.    The service comes back.. I was impressed.

The next day its working when I leave for work.   I come home it is out again.

Another call to ATT, same script again and all they will do is schedule yet another service appointment. 

Again.. they don't seem to be able to determine the scope of the outage.  My previous cable internet company had no issue doing this. 

How do I get past this level of support for a issue that is ongoing ?

It has been 3 days now.   I don't think I can do this a third time.