Unknown Dmc5, damaging credit score

Can someone please explain what is this Dmc5 which are appearing on my credit profile, it's damaging my credit score and I have no idea who they are, I also see alot of reviews regarding this company but no one seems to respond to reviewers, or even Company contact details to contact them and find out who they are.. I can't find no email or any contact information to contact these people, please "helloPeter" assist