App won't work

I'm forced to download the app to do an upgrade. I can't. I've deleted what I could. She can't figure out a way either to make space. They have wanted me to get the app for months. Apps used up all the space on my old phone. I've moved to websites since none of my apps can update. The rep says we must use the app. We tried the website. The website wants me to download the app. I have no space to download the app. The rep says we have the new system of using the app. We cannot find a way to create a tmobile id on the website. It has only log in. She tries to get her coworkers to figure out where it is.

I remember I have my tablet with me. She is happy. We use the app on my tablet and cannot get it to process my payment. Over and over we checked. It refuses to take my money. We try the website. It cannot take my money. We finally use what she calls the old systems. It goes through. We did all that work to use an old system. She says she is sorry the app was such a hassle. She informs me the options of the old system will be gone. They moved everything to the app. She didn't know the website would constant reinforce the app. I'm shipping a 512. I don't understand why Tmobile is 100% on the app when websites work perfectly fine for me for about eight months.

Tl; dr: I need to upgrade my phone. I have no phone space. I'm required to download an app I can't do. Website doesn't work. I do not understand why the company is 100% doing the app when a website can work as fine. Website wanted app.