The Fair Debt Collection Practices Act prohibits debt collectors from using unfair or deceptive practices to collect overdue bills that a creditor has forwarded for collection, even if those bills don't result from identity theft.
You can stop a debt collector from contacting you in 2 ways:
Write a letter to the collection agency telling them to stop. Once the debt collector receives your letter, the company may not contact you again with 2 exceptions:
They can tell you there will be no further contact
They can tell you that the debt collector or the creditor intends to take some specific action
Send a letter to the collection agency, within 30 days after you received written notice of the debt, telling them that you do not owe the money. Include copies of documents that support your position. Including a copy (not original) of your police report may be useful. In this case, a collector can renew collection activities only if it sends you proof of the debt.
If you don't have documentation to support your position, be as specific as possible about why the debt collector is mistaken. The debt collector is responsible for sending you proof that you're wrong. For example, if the debt you're disputing originates from a credit card you never applied for, ask for a copy of the application with the applicants signature. Then, you can prove that its not your signature.
If you tell the debt collector that you are a victim of identity theft and it is collecting the debt for another company, the debt collector must tell that company that you may be a victim of identity theft.
While you can stop a debt collector from contacting you, that wont get rid of the debt itself. To dispute the debt, its important to contact the company that originally opened the account, otherwise that company may send it to a different debt collector, report it on your credit report, or initiate a lawsuit to collect on the debt.