This is a user to user community. It will be necessary to contact Adobe directly once again. Click the following link and scroll down the page to Individual. Then click “Sign in to contact us” It should be possible to start an on-line chat with Adobe Support. https://helpx.adobe.com/support.html
In December 2 2019 I using this exact "chat" support and asked "Hello, I'd like to upgrade from my current annual 20go Photography plan to the 1tb one but I can't" then 24h later an automatic message "our client support is now closed blablabla"
Then yesterday morning I asked again, and again I receive a "our client support is now closed blablabla"
How many months does it takes for Adobe support to answer paying customers haha?