tmobile website/app unable to upgrade phone error

I want to say that for the last 3 years whenever I have tried to upgrade my phone using the app like T-mobile always pushes to online I've never been successful. During the iPhone launch of iPhone 13 is no different. And needless to say that I have tried on 4 different devices. iPhone, iPad, MacBook Pro, PC. All having the same issue. This seems to be a similar issue back in 2018 as many others have reported. This isn't an isolated issue. I tested this out upgrading a non promotion item like an Apple Watch SE and got the same thing. During the launch yesterday from 9am-2pm I have tried endlessly to keep hitting try again and switching to different devices to make sure it just wasn't flooded with people. I'm sure by now the day after the launch there shouldn't be too many people trying to get the new iPhone but still T-mobile should have the money and technology to handle a million requests a min at minimum. And for the hours spent on this issue this is a sad display. I want a resolution on this matter as a subject expert in tech myself this needs to be resolved immediately!