Standard bank vehicle and asset finance

Standard bank vehicle and asset finance are really testing their clients. An amount will be deducted from my account every month via debicheck and standard bank will call me and tell me that the account is in arrears. Then they call and say their system had some issues and they see i have made the payment and it will be sorted. Today a lady calls me and states that my account is in arrears but they see i have made the payment it only allocated on the 9th of December. I have accepted their terms and i am followings through on my agreement the funds leave my account and i still get harassed by them. How does this work? Why does one person call me and say they see its in arrears i provide evidence of the payment and another will call to say its a system problem and the other will call to say its still in arrears. The institution makes the payer feel like a ******** because they call at early hours to tell you nonsense.