I don't understand the point on telling someone you're underage, knowing full well that minors are not allowed on adult websites and knowing that they cannot legally interact with a model? And it's hard for me to imagine any situation where this would be considered a good idea? I can't even imagine a situation where it would be a joke. I mean, most of the time I've seen it done, it was usually so someone could play out an underage fantasy or as an attempt to unsettle the model, and both of those are super-duper-Nopes and frankly pretty gross behavior. Plus, it can trigger an unsuspecting model who may have bad experiences in their past and bring up all sorts of pain. So yeah. Of course, you were banned. This is one of those situations where I kinda have to say, "It sucks, but you bought the ticket, so now you gotta take the ride." Actions have consequences, and pretending to be a minor illegally interacting with an adult means you're not allowed to interact with any of the models anymore.
They probably aren't going to give you your accounts back because they cannot risk it. If they knowingly allowed a minor to access their website, they could be sued, they could get shut down, and all of their models would be SOL. They can't take that risk which is why that's a very hard limit for them. It doesn't matter if you suddenly say that you are over-age, that you are an adult. It doesn't matter if you offer to show an ID - they have no way of knowing that's you and not an ID/credit card lifted from a parent. When you tell two conflicting stories, they HAVE to believe the story that could get them in the most trouble if it were to be ignored. It's safer for them to believe the Underage lie than to take your word for being an adult and suddenly allow you free reign on the website again.
You crossed a preeeeetty big line, and I am sure you made that model, and everyone in her room, super uncomfortable and probably ruined the entire vibe. It's impossible to put on your sexy face and make money if you think for a SECOND there could be a kid watching. So what you did was Super Not Cool, man. But in my experience, that's USUALLY the intention behind such a statement. And people who think it's funny to make models super freaked really don't deserve to interact with said models either.
Find a different site. Be smarter. Don't pretend to be underage.