What is going on?

Around the 15th of last month Cell C debited my account for my payment that WAS DUE. About two days later the money was returned to me by Cell C, that same evening I called their Customer Care Line to inquire if there was a problem and as to why that transaction was reversed. I spoke to the consultant who then informed me that everything on their system was in order and I was up to date with my payments. About a week ago Cell C suspends my account due to my account NOT being paid! Can someone please help me and tell me what is going on???