Poor service delivery

The service delivery is absolutely pathetic. Been paying my car in advance by about R 1300.00 yet the balance does not really reduce. Instead, I am being told the additional payments got into another side of my account which is over 33k. then i am being told they brought this amount back into my account, however instead of reducing my outstanding balance the additional payment i am making is only used to reduce the terms. I then asked for a settlement discount onto the account, i have been waiting for couple of days now, no one comes back to a person, when i wanted to speak to a manager I am being told they do not accept calls, however my call will be escalated to a manager. Now we are on the 22nd of the month, with the delay I cannot settle the vehicle and I cannot stop my debit order to go through as I don't have the amended settlement letter. This is absolutely poor service and being treated like this is un acceptable. Yet we are quick to offer finance onto vehicles.