My carrier is ATT and, up until last week, I was having no problems accessing the MyATT website to check usage and pay my bill. Then, last Thursday I was unable to log into the web site after installing MyATT app on my phone. No amount of tech support was able to resolve the problem. I changed my access ID and password and that allowed me to log in, but not view my account. Apparently, changing the access ID created a secondary account that needed to be linked to the primary account(which I couldn't access!), when I tried to link the new ID to my phone I got an error, that number is already linked to my ID. Fast forward to today, apparently ATT has instituted a new system which none of the tech people have been trained on so no one could help fix the problem. After multiple temp passwords were sent and none worked I finally asked tech support if they could simply delete the primary account info and use my new access ID as the primary. That fixed the problem. I think the app overwrites the web site info stored in their database. It's all fixed now,, but it took nearly a week to fix it. BEWARE!