SERVICE DELIVERY

I AM A CALL C NETWORK AND HAVE BEEN GETTING FREE MINUTES EVERY TIME I RECHARGE AND COULD CHAT ON WATSSAP FPR FREE WITH NO ACCOUNT BALANCE. NOW ALL OF A SUDDEN THIS DOES NOT HAPPEN AND I USE FROM MY FREE MINUTES TO CHAT, WHEN I CALLED THE CALL CENTRE THE AGENT SIMPLY TOLD ME SHE DOESNT KNOW HOW THAT HAPPENED. AND THEY ARE EXPERIENCING PROBLEMS WITH CELL C. HOW IS THIS POSSIBLE THAT I BUY R12 AIRTIME AND IT LASTS FOR ONLY 1 DAY. WHEN I CHECK MY AIRTIME BALANCE IT IS R0.00? I AM VERY DISSAPPOINTED IN CELL C AND AM ACTUALLY CONSIDERING CHANGING MY NETWORK!