I would first contact the FTC or Federal Trade Commission and then file a police report. The best thing to do of course is speak with their manager but if that doesn't solve the problem you can either sue them or go to FTC. Either way is helpful.

You should contact the phone company first and dispute the charges. You may want to take a really good look at whatever paperwork you have. Hidden means exactly that; the legalese may be in mice-type but not illegal. The collectors aren't committing fruad. They're coming after you for the charges you haven't paid. Even if the charges are invalid, that's an issue to take up with the phone company. Right now, the collection agency is pursuing what they believe to be a legitimate debt. If you don't like their calls, you can ask them in writng to cease phone contact and correspond only in writing and they have to abide by it. However, if the charges you're worried about appear anywhere in your phone contract, you are unfortunately liable for them. If it does turn out these charges are bogus, you need to get that in writing and present that to the collection agency. After you present evidence to them that you are not responsible for the debt, they must stop collection efforts. Even if you file a letter of dispute with them , they must stop collection efforts until the dispute is resolved. This is part of the Fair Debt Collection Practices Act, a federal law. Good luck.