Terrible service

Yesterday I went to the FNB in Irene Village mall. Like usual, only one teller is fully functional. And a long que. Which could be ok, but the client at the teller, is doing one transaction after the other. First question. How come there is always a problem with the said branche's tellers. Second question. How can someone be allowed to hog the teller for 45 minutes, doing at least 15 transactions, while I was there. When asking the management, the response was that they cannot offend and chase away one customer. Well. In that time, more than ten other customers was offended and turned away., Is that fair? It is always a mission to do deposits at the said branch, as there is always some problem with the atms