Since I am an overseas call centre op, allow me to voice my opinion on what I think.
From my experience, some of the customers do not give clear instructions e.g. mixing standing orders and direct debits and scold us when we ask if they meant the other thing.
Another problem is when people call on why a charge has been placed on an account, we explain to them but they are not happy. They ask us to monitor their account for them. Why don’t you monitor your own accounts for a change and avoid them from going overdrawn? Simple solution to your problems!