Unhappy

So I never had a problem with telkom until today. I have a contract with telkom and my debit order goes off on the last day of the month. Today all of a sudden it goes off and it takes double(my last money) for the month of march and april so I enquire and they tell me it's an outstanding balance of the previous month, i then asked them so why didnt they just take the previous month outstanding balance cause there's still two weeks before the end of April for the next debit order. I phoned them before hand to change my banking details and when it came to the end of the month my debit order still went off on my old bank account then returned again. My problem is why didn't they take it from the bank I changed it to and why didn't they keep in contact to tell me I need to settle my account or pay it manually like the consultant told me today because all along I thought my debit order went off. I am really disappointed its my last money and all they say is we apologize. I signed a contract for the end of the month not the 13th so why did it go off on the 13th ? Another thing I have my contract 7months already and I never got the power bank I'm suppose to get with my J7 prime