Annoying call centres

I am constantly making arrangements with consultants from African bank. I received over 20 calls per day from day. Each time I make an arrangement it is not recorded, then another agent will call me. They even go to a point of calling after 6am, as if a person does not have a life. On Saturday, 2 April 2016 I said I will pay R1000 in April, until my financial situation is sorted in May. Somehow that information got lost. Today on the 4th of April I am getting thousand calls. Are they not supposed to record my arrangement? It is really annoying and affecting my work.