I suggest everyone who signed up for that Fortune 500 site to call Monday and demand they cancel your trial along with the other two "free trials" right on the spot. And then bring up a few "friendly" points about their T&C if they want to demand you to send in that form.
1. The email address listed is invalid. You tried numerous times to send them an email to the email address provided, but it bounced back to you. How can you notify them of your intentions to cancel if the contact information provided isn't valid?
STRIKE 1
2. What is it? Three or seven days? The T&C flip flop between a seven and three day trial. Legitimate companies have a firm trial placement, this is does not.
STRIKE 2
3. Subscriber may cancel at ANY TIME prior to monthly billing. Calling and requesting your trial is a reasonable cancellation request which most certainly falls under the "any time" requirements. You can't say that, but then say "Oh but you have to send in a form and wait 21 days for it to cancel." That is DEFIANTLY not "any time".
STRIKE 3
Then kindly refer them to Consumer websites where people complain about their shady practices. And that any lawyer would LOVE to represent them in a Class Action Lawsuit that they can and would win, especially once a judge hears peoples stories and then read the company's T&C.
And then read them this line from their Terms
If at any time Subscriber is unsatisfied with the product or service provided, it is Subscriber's responsibility to notify Company to allow Company to rectify any problems or to cancel the Subscription. As the Subscription is provided on a month-to-month basis, it is Subscriber's responsibility to notify Company prior to payment of monthly fees. Payment of ongoing monthly fees signifies Subscriber's satisfaction with the Subscription, previous months billing, and all products and services provided to that point.
And at this point, tell them that this is your official notice that you want the Subscription canceled, you do not want to be billed and you expect to see a confirmation email of your cancellation immediately. And if they don't comply with your cancellation request, you will call back and they will be hearing from your lawyer. (even if you don't have one.)
You might get lucky and get someone who will be scared shitless over this a will go ahead and process your request. Trust me, they have a link or something on your account profile that they can click and cancel your account in five seconds tops. If not, demand to speak to a supervisor and/or keep calling back.