Insecure loan for Multichoice decoder payment plan

I have Multichoice account for more than 20 years Last year August I upgraded to the DStv ultra decoder. I have been paying my account monthly without a fail.Last month Multichoice decided to list on credit bureau as a non payer. I have contacted them several times no one can help because they deny the itc listing. My bank confirmed that it’s Multichoice that listed my account as a insecure unpaid loan. How can I get help