Unable to cancel payment

Jetpack emailed me to say they will take the payment for my upgrade next week. I no longer have the plugin, and there doesn’t seem to be any way to contact them. The link to ‘my account’ takes me to a wordpress.com site, which confirms that I have no current purchases.

Help! Please! I have little enough money, definitely cannot afford to pay for something I don’t want and don’t have.

The page I need help with: [log in to see the link]