@Marcus-Mortensen Hello!
I too have been frustrated in the past trying to cancel stuff in PayPal. Maybe you were already on this page, but just in case not I figured I'd share this URL:
PayPal automatic payments management
It's irritating to track down in PayPal sometimes but this lets you manage who is preauthorized for subscription payments. If you delete something in here, even if the vendor ignores your request to cancel and attempts to bill, it shouldn't go through for them. I italicize that because it's just in theory - I haven't had a problem vendor yet requiring me to test this but once you revoke authorization it should work.
Just wanted to share that page for future reference. Sorry if you already found that and this is just useless info.