I want to sign up for spotify premium but it keeps telling me that my payment method and country don't match but it won't let me change my country to US. I'm on MX using an wells Fargo card to sign up.
Have you tried to use an incognito tab, clear the cookies of your browser and use another browser or device?
When this doesn't work, you should try to use another internet connection (e.g. cellular data instead of WiFi).
Have a nice day!