Ok, the only way to unsubscribe is by calling their support hotline. It should be free, but I'll find out if I get a bill from that soon. It is 1(888) 824-3640
Tell them what you want: You want to cancel your fling.com subscription
They will offer you another trial subscription. Say no and make sure that you say you do not wish to remain a customer and you will make no further purchases. That way they can't misunderstand.
After that, they'll tell you that the subscription is cancelled. Make sure with the support person that there will be a confirmation email sent for Fling.com cancellation. I got my cancellation email. I'll also be calling the bank to keep an eye out for unsolicited charges to my account. I'd advise you do, too. Hopefully, this will get you out of the nightmare. Good luck!
P.S. please be nice to the support person. They're not directly related with Fling, but I'm sure they get all the flak for it. It'll also keep them from "misinterpreting" you out of spite.