They are required to mail you a letter containing their information and the information about the alleged debt as well as your right to dispute the charges within 30 days of receipt of that letter.  This has all the markings of a debt scam.

Federal law (FDCPA) requires them to send you a letter (US MAIL ONLY) within 5 days of their first contact that contains their name, physical address, the creditor’s name, and the amount of the alleged debt.  It also must contains “mini-Miranda” telling you that it is an attempt to collect a debt and that all information will be used for those purposes.  The one other important thing that this letter must also have in it is that you have a right to dispute the debt within 30 days of receipt of the letter and if you do so, all collection activity must be stopped until the debt is verified.
Read up on your rights here, get template letters to send and also make a complaint at this government site: http://www.consumerfinance.gov/

Also file a complaint with your State Attorney General's office.
List of State AG’s offices:  http://consumerfraudreporting.org/stateattorneygenerallist.php

Debt scam. I put in the call type they are a debt collector because that's what they claim. But it is a false claim of debt. Don't give them your bank details!!! This is a scam!!

No answer. ..