Harassment ~ demanding payment on a fully paid avcount

Cell C I have just received this sms from Cell C "Cell C has reported the non-payment of your account to XDS, a registered credit bureau. Please call 084140 urgently. For cash or EFT payments, please use the following ref no: ***9." MY ACCOUNT IS PAID IN FULL (SEE ENCLOSED COPY OF PROOF OF PAYMENT VIA EFT) I've been using the reference number in their sms for all my payments, so IF THEY CHECK THEIR BANK STATEMENT, THEY WILL FIND MY PAYMENTS. I'VE ASKED ON 14 AUGUST 2019 ALREADY FOR A MANAGER TO PHONE ME. 5 DAYS LATER THEY HAVE STILL NOT ADHERED TO MY REQUEST AND NOW I RECEIVE THIS SMS????????? I will now flood their Facebook page and place this comment on all their posts so that people can be informed of what they are busy with. I am also going to seek legal counsel and go to the press. YOU HAVE NO LEG TO STAND ON. MY ACCOUNT IS PAID IN FULL. SORT OUT YOUR PATHETIC SERVICE FOR ONCE AND FOR ALL. YOU ARE PATHETIC TO SAY THE LEAST!!!