Un updated Records

Had a builders account which was in arrears was handed over to MBD attorney's which I paid up in April 2015, I sent the paid up letter to RCS for record keeping and to update their system, September 2015 I receive a statement from RCS that I owe them R6000 and I've been handed over to Daly Credit Corp, which I then sent a paid up letter to them too and also called their call centre to rectify this, still no luck, its the 29 September I still get calls from annoying debt collectors to pay money that I don't owe, and I'm being told they'll fix it...scared this will affect my credit record......Ref ***