LWM

This company has been hassling me about a debt going back to 2014 They LWM Claim I have not paid FNB? Since 2018 So I told the intelligent human that called me it must be prescribed debt as I NEVER EVER RECEIVED ANYTHING FROM FNB SO SHE POLITELY TOLD ME THEY ARE GOING TO ISSUE A 129 AND BLACKLIST ME I sent NATIONAL CREDIT REGULATOR A WHATSAPP STILL AWAITING REPLY What can I do to stop them hassling me Also an amount of R1600 was mentioned by LWM that I SUPPOSEDLY PAID IN 2018 I MUST HAVE ****** MONEY TO PAY THEM AS I AM A PENSIONER PAYING 12 CREDITORS WHO PAID THE R1600 I WOULD LIKE TO THANK THEM MOST SINCERELY AND AS FOR LWM WHY AFTER I HAVE SRNT THEM NUMEROUS WHATSAPPS don't they contact me and let me know what is happening