Services like this are the reason I prefer to pay thru google play. It is much easier to just cancel it
It's a shame credit cards don't offer the same thing (Chase is able to list them all but provides no contact information or ability to revoke authorization)
One of them can also create zero-cost virtual Visa Golds in a couple of minutes. If I need to use a really sketchy service, I simply create a throwaway card, put a bit of cash there, pay for what I need, and then delete the card.