Why iam i owning rosepark hospital

I am getting harassed by Graham Attorneys almost everyday now over what i dont know They claim i owe Life Rosepark hospital Bloemfontein an amount of R548.10 which i strongly not agreeing with them because even when i call hospital to ask them how much i owe them and for what i owe them for them nothing as per thier records I kept on asking this guys what is the amount you claiming i owe for they got no answer to that question all the times Now they treatnishing me that they will list the account on transunion The next thing my name willl be listed on credit report as a bad person