Why can't I switch plans???

Please go to Adobe Customer Service (Make sure to sign in to your Adobe account first and allow popups on your browser. You may not be able to see the chat window if using a VPN.):
https://helpx.adobe.com/contact.html?rghtup=autoOpen will automatically open the chat window.
Type "Agent" in the chat box to bypass the chatbot and be connected to a person.

You may also be able to contact Adobe by phone:
https://helpx.adobe.com/contact/phone.html