Cobol illegal dealings

Hi everyone i am being constantly harresed by debt collectors appointed by cobol finance for an account that has been PRESCRIBED for almost 7-8 years at which at the time of my retrenchment at the company i was employed at the time i have forwarded my relevant paperwork to COBOL and did not receive any form of contact from Cobol up until last year at about this time of the year from MDC debt collectors ( Who is a company that buys PRESCRIBED debt from companies and ILLEGALLY try to collect money from accounts that is not even listed on any bureau) and have told them on various occasions that what they are doing is ILLEGAL not that it stopped them from sending me countless emails and sms's along with phoning me up to 5 times a day basically trying to force me to make a payment and some of the agents even getting rude and having massive attitudes when you lay the law in front of them... Now i am getting harresed by a company called JER 31AND ASSOCIATES RECOVERIES for payment which i am not liable for as the debt is prescribed i am going to report COBOL FINANCE along with JER 31 AND ASSOCIATES to the CBA OMBITSMAN if the harresment of the ILLEGAL act of trying to collect payment for debt that according to the CBASA does not exist hence not being listed on any BUREAU of S.A