You seem to be doing all right so far.
Do not send them any payment UNLESS
they can VERIFY your DEBT. These could
be "slimy" bill collectors. If they send you
a summons you either showe up to court
or you fight the "service" of the summons.
Look up "service of process" in your MD
Court Rules (at local law library or general
law library, or internet). Whatever you do
DO NOT IGNORE these yahoos as they
could get a "default" judgment on you.
And correspond in WRITING not on the
phone. You'll need PROOF you communicated
with them for court, etc.
THIS ANSWER IS PURELY FOR ACADEMIC DISCUSSION ONLY AND DOES NOT CONSTITUTE ANY TYPE OF LEGAL ADVICE OR LEGAL REPRESENTATION.