@Gregor977TM
You need to reset the password on the linked EA account that account has the persona gregor977 (not Gregor977TM your posting on now) that EA account uses a Mail email
use the following link to reset the password https://signin.ea.com/p/web2/resetPassword then login on that EA account to fix the swtor account for purchasing
for future purchases, use incognito mode on chrome initially if you purchase on swtor.com to be sure browser cache and cookies is cleared
Support cannot see an email from the email address on the swtor account , try resending firstup , however it will be tomorrow before i can check if it arrived (1am here)
call swtor support if an option you can ask to upload the screenshots to a ticket whilst on the phone https://answers.ea.com/t5/General-Discussion-Technical/INFO-Getting-Help-and-Board-Guidlines/td-p/4806237/jump-to/first-unread-message