Mtn user's

Today is the fourth month with my contract with mtn .... I have agreed for then to do debit order on my CV in the 25th of each month every since I started this contract they have been taking money on all other dates besides the 25th even gave them grace until the 26th I've Missed payments twice because lack of followed agreement made with a consultant in January i arranged with mtn to do a double debit order on the 25th of January 2018 they only took off for one month .... After going to mtn asking them if I can pay them cash because I see they did not debit the money like I've ask them to the consultant then told me to my pay cash because I've already made arrangements with then to do a debit payment so they will do a double payment and he said to me just to wait a few days I then waited and nothing happened then 27th February they debit for two months that I was not prepared for .... Because by the 27th I had already transferred money from my one account to the other so there was not enough money in for the entire amount which means it will bounce back and be a unpaid 2minths all because they can't stick to the debit dates I agree or authorized them to .... I am responsible for payments but they are not adhering to my wishes from them .... I authorized them to debit on the 25th because I know there are other activities happening after that date even the 26th for the latest .... So now I am an unhappy client with two months outstanding because of their lack of listening to what I've asked .... Do the debit the 25th or even the 26th after that there will not be enough .... And why did they not follow through with my arrangements that I've made in the month of January why did they just do as they please instead of doing what we agreed together in .... I'm very upset .