Incorrect billing

I normally pay my account via EFT as per agreement with Vox . I make sure that my payments are before the 1st day of the month. In October I paid my account on the 31st and sent vox proof of payment as per normal. To my surprise I get an sms from my bank on the 1st of November that viz tried to do a debit order which we didn’t agree on . I had already paid them why are they going into my account causing me bank charges and they have the nerve of saying I owe them 28 rands for what I don’t know. Can vox please sort out my account and refund my bank charges as I have never agreed for debit orders and I pay them on time every month.