Vodacom the ****mers

I took a fibre contract with Vodacom and gave them my bank details to debit their money every month, unfortunately they do not deduct their money monthly as agreed on, instead they will send a complaint to creditscore or experian as I am a bad payer, worse part they want it to be on arrears so that they can charge interests. When I was at home when I see they did not deduct I would go to their branch and pay , they are making it difficult for me now since I'm out of the country.