Cancelling the auto-renewal of my subscription

I forgot that I subscribed to AVG Internet Security and have recently been billed, I'd like to cancel my subscription but when I try on the website I've followed all the steps correctly but it says I don't have a payment history or any subscriptions. On my application on my computer, it says I have a subscription but there's no button to cancel. I'm using the same account on each but no luck. Please just cancel it or tell me how I can do it myself.

Hi Evan,

We're sorry to know that you've decided to cancel the AVG subscription.  
However, upon checking your account, we're unable to find any subscriptions. It might be registered under your alternate/old email address.
Since, it isn't recommended to share the account info over this public post, we've sent you an email requesting the info.
Please revert to us via it to proceed further.