FNB home loans abusive and harassing

Home loan accounts fell in arrears for unknown reason. Despite numerous attempts no-one at fnb seems able or willing to investigate the reason for the arrears. Receives at least 10 phone calls from home loan collections on a daily basis, resulting in me blocking the number. Communicating to 3 persons via email, but none are able to advise why accounts are in arrears. The just request me to enter into a payment agreement to fix the arrears. I need to know why the accounts are in arrears before I will discuss corrections. IF ONLY SOMEONE AT FNB WAS WILLING TO INVESTIGATE AND ADVISE. BUT INSTEAD THEY JUST THREATEN AND THREATEN. What an absolute disappointing lot and traumatic experience.