Business Account that can't see their bill online or add devices

So our growing business has over 100 devices from our two accounts since last year. As of current, I have to call to order devices and the process takes forever. However, we're never able to get a breakdown of our bill but we can see it on our statement. When we go to the website, it just shows us a $0 bill with no upcoming payments but we've been getting billed for a while now for hundreds of dollars a month. We also should be able to add devices/plans online to be delivered but when we start the process, it gives us an error and asks us to call. 

As we continue to grow, we can't continue to call in  and spend hours devoted to that. It takes almost an hour per device and we normally need to add up to 5 at a time which begins to get frustrating after a time having to stay on the phone for hours a in a day.

When i call in to fix the problem, they can't seem to fix it and won't call me back after they mention they will. 

Help??