I've been unable to download and app to my phone for one month till this day.

I cannot enter to the App Store since the last month. I've checked all your points in this link: If you can’t connect to the iTunes Store - Apple Support but is no use. My internet connection, time zone, phone's software, user and passwords had always been right, yet, i cannot enter itunes/app store. I demand a quick response since downloading apps on your phone should not be a problem to begin with.

My phone is a 5s with software 9.2 model