PAYING FOR NOTHING!!!

I just renewed my contract in October for unlimited data and router and asked them to changed my debit order date to the 15th. They failed to debit on the 15th, I made an EFT ono the 19th of October and called to inform them. since then i have been receiving messages that my account has been handed over to the debt collectors even after the payment. I have been struggiling with the network since July and kept calling but this matter has not yet been resolved i didnt get any help, instead i get threats messages and emails from debt collectors. i am really tired because each and every day i have to call them with no help. i will report this matter to ombudsman if this matter is not resolved!!!