Can't upgrade to premium from unlimited! "Payment details error"

[raimostaja]

Hello! I've got Spotify unlimited subscription.  I would like to upgrade to Premiuym subscription so I could listen to music on my phone. When I go to upgrade page, it confirms that "You have 60 days left on your Spotify Unlimited subscription, these will be converted to 30 days of Spotify Premium. After 30 days you will be billed 9,99 € per month." 

However when I'm trying to click the "Upgrade my account" button @ https://www.spotify.com/fi/get-spotify/upgrade/ I'm just getting error "It looks like you've not added payment details to your account yet. Please add your payment details here." But when I check the payment methods page, I can confirm that my Mastercard details are there, and it is fully working card, since it allows me to buy more "unlimited subscription time". 

Anything else I could do for now? Kinda would like to get the premium subscription fast since I'd kinda need it tomorrow (over 12hours in a airplane..)

[raimostaja]

Upgrade: Actually if I look my "payment method section" now, it looks like there's no any payment methods added. However if I re-enter my card details, I get the message "Your payment details have been stored. No money has been withdrawn from your account. Your new payment details will be used when you are next billed for any current subscriptions or when you buy any new products. " 

But then again if I look the payment method section again, it still looks empty. What's wrong? 😄