Hi @owengovenlock23, I'm sorry you're having this issue, I'd advice you contact support so they can manage your account and check why you were charged full price. Remember, if you've previously used 30 days free trial or 7 days free trial, you're not eligible for the promo.
You can contact support by filling this online contact form: https://www.spotify.com/about-us/contact/contact-spotify-support/
If you receive an automated email directing you to the community and/or help boards, make sure you reply directly to that email (even if it says it is no-reply) and an agent will get back to you as soon as possible.
