I called number and got automated recording for WCA customer service - a special offer service provider. I don't know if person who had my number before me was a subscriber (as that's how they refer to you when you dial in) or if they use that as a ruse. Anyway, they guide you through how to cancel request for service and say it takes seven days. I just did it - we'll see.
Calling scammers back only confirms your number. Apparently you let them trick you into thinking you could unsubscribe from something you never subscribed to in the first place.
Don't call them back and don't go to their scam websites. Help shut these crooks down for good.