How the heck do I cancel Avast anti-virus autorenew? [View all]

My wife got suckered into a subscription for Avast while staying at a hotel a few months ago. By default, it keeps auto-renewing even though she's not using it. Trying to turn off auto-renew, you enter purchasing info, press "manage account", and sure enough, there's an on/off radio button for auto-renew. Clicking on "Off", you get an "Are you sure?" window in which you can't actually select anything. Here's the thing: every time you select "Off", you get that window WITH NO WAY OF ACTUALLY SELECTING "OFF"!

This strikes me as straightforward consumer fraud, but, short of telling our bank to cancel the payment, how do I actually turn off auto-renew?

Google is no help. The first x returns all point to avast, and then there's a youtube video in which somebody simply selects Off and everything works. Well, I can't seem to manage it.

Hints? Thanks in advance.