Can't Cancel Automatic Renewal

After entering my order number and password then clicking on “Manage Order” I am asked to enter my email address and account password. This gets rejected with “Invalid email address”, even though I can successfully log in to my account elsewhere and see that my email address has been validated. Sales pathway is Digital River.
I note that similar complaints have appeared on the forum since early 2015 and it appears nothing has been done to rectify the problem. I suspect that this is because automatic renewal is to the financial advantage of the vendor. But, dear vendor, your customers don’t like automatic renewal of annual subscriptions. And if not satisfied, those customers may well permanently cancel their subscriptions and go elsewhere.

https://www.avast.com/faq.php?article=AVKB24#idt_010 (Cancel auto-renewal)

The link you provided doesn’t show what to do if it says the email isn’t valid even though it is.

But, dear vendor, your customers don't like automatic renewal of annual subscriptions.
If they don't like it, they should not put a checkmark in front of it when purchasing a license.

I deleted my account b4 renewal as my internet provider provides Norton in my service, I got screwed out of $39.99 how do I get a refund? This is bad business. Submit a ticket does not work, ty jrfreebyrd@gmail.com this was on 1/3/2016

1st I suggest you remove your email address otherwise it is likely to be harvested by spambots.

Try the following: Support Ticket Refund - https://support.avast.com/support/tickets/new?form=2.
Support tickets are handled on a First In First Out and can take between 5 and 10 working days, depending on payment method. Whatever you do don’t submit multiple tickets as this throws you back in the line.