As title says I saw an advertisement which advertised for a free 30 day premium, I clicked it and it asked my credit card info, I put them in and I got charged 10€
I want a refund of the 10€
I suggest you contact support so they can help you https://www.spotify.com/about-us/contact/contact-spotify-support/
If you get an automated reply email telling you to check the help section or the community, you need to reply back to it, even if it's from a no-reply address.
Support usually replies within 24-48 hours.