A streaming service I'd forgotten I subscribed to signed me up for a year for $20. Without any recent notice or warning that I can find (yes, it was in the fine print at the beginning), they renewed it for four times that amount.
The best thing to do with these services is to cancel immediately when you subscribe. Force yourself to manually renew, or you'll find yourself paying a lot more than you planned.
My AmEx does that for me. When I'm paying for something online, I can request a virtual card from them, and it's only valid for one transaction. If someone tries to use it again, it's automatically flagged as a fraud charge.