Telkom debit order

i took out a phone contract with telkom January and my debit was to begin February 28.Came that day they never debit the money,had to manually pay.Following month same thing happened now with extra charges saying that i don't pay on time that's why there's extra charges.What i don't understand is that there's always money in my account i don't get why its not taken honestly....im so furious....everytime month end i have to call them with no assistance...they're telling me that i should check with my bank which i did and the debit has been active Telkom is seriously ruining my credit profile I will never recommend telkom contracts to anyone I cant wait to be done with them any part ways.