Wrong information loaded to my Credit profile

VERY VERY Bad.

RCS cards have loaded someone else information on my credit profile,when i called them to remove this information from my credit status witch is not my account they said I had an account with them some 12 years back so I must send them proof that tis account has been closed and paid before they can remove that account that is not mine from my credit profile.What do they not understand.POINT1 this is not my account and details that they have loaded POINT 2 Remove this from my credit profile

what is so difficult they have made a mistake now I must gou out of my way to fix their mistakes