Hey! Welcome to the community 🙂
You can remove your card details from Spotify while you still have an active subscription. You need to cancel your subscription first from your management pages (bottom option).
As for being charged, don't sign in and use the premium and get in touch with the customer services team directly using the online contact form as they will most likely be able to refund you.
If you get an automated email reply back directing you to the community or help pages, you need to reply directly to that email (even if its from no-reply) and one of the customer services agents will get back to you as soon as possible.
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