It sounds as though you're in the same position as JasonRobert:
http://www.absolutewrite.com/forums/showthread.php?p=3273445#post3273445
He received similar advice here across a couple of different threads. He has since chosen to delete many of his posts.
As to gaining a release, just use your personal web page to keep posted all correspondence between you and PublishAmerica. Let the world see how poorly PA behaves. It might not result in an immediate release, but the more sites that show how bad PA is, the more likely they'll release you and others so they can counter your sites as sour grapes. Just don't pay them for a release.
What Dave said.
Post their e-mails in public so the world can see how they treat you.
DO NOT pay to get our of your contract or buy more of your own books. That's what they want.
I'm sure you'll receive a lot of similar advice from members here, and all well-meaning. And if you want to take that approach at the start, posting their emails and taking a confrontational approach, that's up to you. Maybe it will work, although no one here can give you that guarantee. Your contract is with PA, after all.
There's a very strong anti-PA lobby here, and I would say think twice before you throw in your hand with it. I'm not saying that they don't mean well or raise real issues with PA, just that their advice may not offer the best way for you to achieve what you're seeking to do, which is to get out of your contract.
Your contract is with PA. If you're not happy with it and want to be released from it, maybe your first step would be to contact them and see whether they're prepared to release you from that contract, and if so under what terms. If they offer terms that are acceptable to you, even if it includes buying books or paying money, then it's your decision as to whether or not you accept those terms. It might be in your own interests, with your book in mind, to cut your losses, pay up, and be free to go ahead from there. Only you can decide whether that's right for you.
If they are not prepared to negotiate your release from the contract, and until you talk to them you don't know - no matter what the experience of other people here, then you'll need to think about what to do next.
The word scam suggests something fraudulent or illegal. If you really believe you have been scammed, as you suggest, consider whether you have any way to address that through the courts. If that's the case, seek legal advice.
Taking a confrontational approach from the start may lead to you achieving what you're seeking in the long run. Then again, it may not. I'm not convinced that all of the advice you'll receive on here will be in your best interests, so you need to think about whether people here are actually serving your needs or pushing their own anti-PA agenda, albeit with best intentions.
By the way, I believe that in the UK emails are automatically covered by copyright. I could be wrong, and I don't know if the same automatic cover applies elsewhere, but you might want to check.
Nothing that I've said above is intended as a criticism of other people here offering advice. That's just the way I see it as someone who observes the PA threads here but has no vested interest on either side. Not all advice offered is necessarily good advice, and people do have their own agendas. If you think a confrontational approach is the best way to achieve what you're after, by all means go right ahead. Your goal, however, is not to bring PA down, but to do what's best for you and for your book.
Good luck.
Cheers,
Rob