Credit Card

I have a very messed up credit card with standard bank and I want nothing but to make sure that I pay it off but with how standard bank's *********** consultants are I don't see that happening soon, thing is I requested for a debit order to go through each month on the 27th but that has not been happening, at times I had to pay cash at the branch or make a transfer, I'm the one always doing a following up whenever they don't debit, sometimes when I call checking why they never debited they tell me that the debit order was cancelled by who I don't know, another thing is that one of their consultants told me that the reason I have been paying non stop but the amount owing not decreasing is because, the money is expected on the 16th of each month but then I asked that how come it's expected on the 16th and not on the 27th as it's the day that I get paid on, she told she doesn't know, I need some answers from someone who knows his/her story and I want standard bank to refund me the interest charged for paying on the 27th and not on the 16th, the account is on a fixed arrangement but they are messing up, can someone talk some sense with me, and I have been paying this acc for too long