Hi @Masterhjort! Thanks for your post here.
If you check your bank statement, do you see a transaction ID next to your January Dropbox payment? If yes, I’d like you to visit this page, and insert it in the given field.
The email address that you get, is it the same as the one you see here? If not, then please open another browser on your computer and try to log in to Dropbox with the email address you see, to check if a second Dropbox account has been upgraded instead.
Let me know what you find.