Hey Originalxxxg, welcome to the Community. I'm sorry somebody hasn't got back to you sooner. Did you give any card details at any point to Spotify using their website, or did you authenticate an in-app purchase using iTunes or Google Play for Spotify Premium? They give you a free trial for a few days, and they charge after that if you don't cancel. You can use Spotify for free, but without the additional benefits.
You may have signed yourself up to a Spotify Premium membership without even noticing on certain phone platforms if you made another in-app purchase in another app a few minutes before. They sometimes don't ask for authentication on some platforms, which is why this charge has come as a surprise to you.
If you've been using Spotify Premium services and you got a membership without noticing, you probably won't be eligible for a refund, but that's at Spotify's discretion. If you could let me know what type of device you're using to access Spotify, and if you're getting Premium service (ad-free, offline listening) that would be great. Hopefully, we can get to the bottom of this mystery. Thanks!