Problems with debit order

I have asked a consultant to book a specific amount of a debit order to go off on my pay date, to my surprise an amount which i did not agree to was debited. I was clear and we had an agreement with the consultant i am disapointed as to why do we still need to speak to someone who will still make such mistakes. Even that recording which calls me every month to confirm my payment keeps on doing the same thing. Now i have to go and reverse the payment and deposit the agreed payment to them which is bank charges time and whats going to happen next month same mistakes again. Im close to finishing my account and this is whats happening. I dont want anything to do with african bank and will encourage people to never get help from them.