harassment regarding my accounts

I got a call this morning from African Bank saying i have not paid my account, i had been retrenched from my previous job and when i started at a new job, I CALLED African Bank and had made payment arrangements with them, this was done in about 2011 & 2012 sometime. anyway the gentleman that called me this morning said i must make payment so i told him what arrangements had been made with African Bank, i cannot afford the full amount instalment and pay what i can afford. he said it doesn't matter i must pay my full instalment, not wanting to listen to what arrangements i have with African Bank on payment terms. i have emailed the customer care a couple of times now , they never send both my account statements to me via email or post, only one gets sent to me. i have requested it over the phone and on email now numerous of times and still no feedback or statements have arrived!!! the gentleman that called me this morning. Anyway the man that called me this morning has NO right to call me and tell me what i MUST do & not listen to reason, i am the client and all my account histroy should be on the system to avoid upset customers should it not???!!!!!