Hey @LouieKleanthous, welcome to the Spotify Community!
If you didn't complete signing up for the discount and if you didn't receive a payment receipt email, the charge to your card should only be marked as pending, which means it should be canceled soon.
If you check in a few days and the charge is still there, let me know and I can help you 🙂
Hey there you, Yeah, you! 😁 Welcome - we're glad you joined the Spotify Community! While you here, let's have a fun game…