Very poor service at summer residence

We have a second home in a resort area where we spend our summers. The cellular service is TERRIBLE!  It’s not always been this bad. We have used AT&T for many years and it’s been the last two summers that it’s gotten really bad. My belief is that AT&T has outgrown their network in this area and that when the population swells in the summer and more users are there performance suffers. 

My my guess is that AT&T doesn’t want to invest in the infrastructure for an area that is seasonal. 

Sonetimes we we can only use our phones outside - they don’t work inside our house!  Sometimes calls don’t go through or if they do our voices are so garbled that no one can understand us. 

We are “all in” with AT&T - wireless, internet, DirecTV - pay over $500 per month. Very unhappy. 

We’ve tried the “Troubleshoot and Resove” and reported many times with “Mark the Spot” but no improvements. Very very unhappy. They should give me a discount for how poor this is in our own home!