Hi have a Premium account and Fry to log in using the spotify Premium account. It worked fine in the beginning, bit now when i enter my password and username i get the message that the username already exists.
If you subscribed to Spotify using your facebook credentials, you can only change your password in facebook. For a hardware device like the Denon, you need to request a seperate username/password from the link I posted.
Hmmm.........if your profile page doesn't show this option, I suggest you submit an online contact form and someone at Spotify will look into this for you. If you get an automated reply, make sure to reply to it directly (even if it's from a no reply) and it will be sent to the Spotify staff.