Disgusted at the level of service

I received a call on the 26 July 2023 @ 10:14AM, informing me my bond account was in arrears with R4 000.00 odd rand. I asked if I could pay it in two separate installments, Half before they 15th August 2023 and the balance before the 15th of September 2023, with a CLEAR instruction to not change anything on my normal monthly repayment. On the 01 August 2023, only R4000 odd rand was debited off my account and not my full monthly debit order? I have paid as per arrangement the R2000.00. Now you are telling me I am in arrears with the normal monthly installment. I have requested on numerous occasions someone senior to call me, this has not happened. Why am I as a client not being treated as a client. Your staff member in collections went as far as to put the down on me and insult me of having insufficient funds. Please go and retrieve that phone call done today 28 August 2023 @ 13:41PM. I am absolutely disgusted in your service. This is how you treat people that are your clients and don't have a small bond with you either. I would like to know who gave you the authority to change my debit order?