Directv App Unknown Error

Since Dec. 28th, I have not been able to access my Directv app to watch live tv on my iPhone or any other device. I enter the user ID and password I have used for years and the app just kicks back Unknown Error and takes me to the App Store as if I need to download the app again. I have called and chatted with AT&T at least five times with each agent promising a resolution within a day, but still nothing. Not sure why we pay such high monthly fees when things included in packages do not even work as advertised. AT&T resolve now please!!!