Tell MCS to stop calling me

I have settled my credit card with African bank on the 01 December 2017 , the account was closed , I also received a paid up letter. Now the people from MCS are calling me everyday with a 031 number telling me that I still owe African Bank R11600. The even threaten to vanish me. I explained to them that I have paid the account , I also sent them the paid up letter I got from African Bank. But they wont stop calling me.

AFRICAN BANK PLS TELL THOSE PEOPLE TO STOP FALLING ME, I DONT KNOW THEM AND I DONT OWE THEM ANYTHING.