This is not how you get a collection agency off your back. These forums are for call recipients to share their experience and optionally offer advice. They are *NOT* direct open channels to the phone bank boiler rooms we comment upon. I really hope that's not your phone number you've used as a user alias. It is unwise to publish a phone number you meant to protect in an open forum where any data harvester and scammer can find it.
I had to look elsewhere to find the business names ARC Management Group and Pollack & Rosen. If you've hired counsel, what are you doing trying to communicate directly with the agency? That's the lawyer's job now, remember? Hopefully you realize that the collector's contact with you becomes illegal the moment they know you have a legal rep.
Some reading on federal laws, in case they weren't made clear ...
official FTC guidance and staff opinions on the FDCPA, PDF copy of the Act
CFPB reiteration of the Fair Debt Collection Practices Act