Mobil share advantage 6GB plan gives only 2GB data usage

This isn't a new plan, but this is a new problem?  

Are you saying once your entire plan data usage reaches 2 GB, no matter who has used how much data, your service for all five of you slows down to unusable speeds?

Not 2 gigs per person (almost) 

And you have checked in your online account to make sure that you haven't used up all 6 gigs?  (which would automatically cap data speed at no more than 128 kbps). Are you calling *3282 for data usage by line number? And the totals are under 2 gigs? 

Is the slow down or termination of data a permanent thing for the rest of the bill cycle? Or does it seem to start and stop for the rest of the bill cycle and some people get data and some people don't?

Thank you for your inquiry. Replying to what you asked

1) yes, it slows down when entire usage (combining 5 lines) reached 2GB. Not any of them over 2GB. For example this month (14 days in my bill cycle) the total usage is 2.28 GB and slows down.  The line using most is 1.07GB. I am getting these data from our account on ATT website

2) once we hit 2GB, the slow down is permanent until the next bill cycle

ATT website and their bill clearly shows that we are on 6GB plan. We talked probably over 10 different representatives of ATT customer support over the last several months. None of them can explain what is going on let alone fix it. 

It is appreciated if someone knows the right people to talk to or how to escalate the claim. 

Since you have already spoken to multiple people at AT&T, I see no point in continuing to deal with the peons who are unable to resolve the problem.  

File an FCC complaint. A routine FCC complaint is no big deal.  It only takes a couple of minutes to fill out the information online. 

The complaint is forwarded back to AT&T upper management, who then will turn it over to somebody who really knows their stuff.  

...... 

It is possible that the service in your area is so congested that everyone suffers from poor data service. However on a 6 GB plan your data service should be prioritized until you have used up all six GB. The only plans who gets higher priority than limited/capped plans would be business plans.   But this isn't something that should affect you at a certain data point, and it wouldn't be an absolute shut off. Congestion is something that happens occasionally and there would be times where congestion would be relieved and data would flow again. I'm not getting the feeling that's what's happening from your post. 

If this is a congestion problem, start shopping for a new service provider.

Thank you very much for your advice.  We will definitely look into this option if other methods are exhausted.

Thanks