Cellc doesnt know my Direct Debit date

Once again i am here for Cellc endless headache I have a direct debit set out for the 30th and they attempted to take a payment on the 28th . I dont use that number but i use it on a spare phone and its always off and use that nunber for whatsapp. Either way i dont understand why cell. Is full of ******* i get paid month end ye they attempt a payment on the 28th . Now i must a missed payment on my credit score ? I want this rectified or im going to the ombudsman . Its so easy for big companies to take advantage of their customers and we cant do anything about it . Because in south africa there is no such thing as customer service