Std Bank pulling me backwards

I received an email statement about an account that I closed in september 2015. I went into the Mowbray branch to find out what this was about. Upon assistance by the front desk person, I was referred to consultant. I waited 45min to see the consultant, the guy before me had been waited for an 1hour already when I got there. There was only 1 consultant working. As a result the wait was unbearably long. I ended up leaving without getting the assistance. Now the issue is I closed that account and received a letter of closure. The bank realised that the mistake was on their part but because of the wait I could not get it sorted as I had to rush back to work. Since the bank was at fault and they have been sending me harassing messages about legal action for no good reason, why is it an inconvenience to me to and now I need to go back again to try and get this fixed. This is the very reason why I left Standard Bank in the first place...poor service and lack of attention to detail.