They are a collection agency for Citibank (may be an actual Citibank dept.) & BREAK THE LAW by violating the Federal Debt Collections Act in several ways:
--Any collection agency that is NOT a law firm (or does NOT have a lawyer on staff that regularly files lawsuits) ABSOLUTELY CANNOT threaten you with legal action (beyond the collection activity they can perform themselves).
--They are NOT allowed to call themselves a law firm or even legal department.
--ALSO, a "CIVIL COMPLAINT" is something a lawyer files in court, and they CANNOT claim to have a civil complaint forwarded to them or to be preparing one.
--They also CANNOT call anyone other than you unless they have absolutely NO WAY of finding you.
--And, if they do call someone else, they CANNOT disclose who they are or why they are trying to find you.
These are just a few of the MANY legal violations perpetrated by this company (perhaps even a dept of Citibank) on behalf of Citibank. DO NOT stand for such behavior -- they CAN and WILL be found legally liable.
Upon the first contact with this company, simply do as suggested above --send a certified letter requesting they cease & desist all contact with you pursuant to the "Fair Debt Collections Act". (If possible, in this letter also try to list the violations they have already committed.) Upon receiving this letter, they can no longer contact you.
Online you can easily find references to this law (including the code section) as well as a list of activities they legally can and cannot do.
Hope this helps!