Bad service and no one seems to have answers

I have had changes made to my provident fund portfolio investments. When I called in to query why the changes were made I was told the reason could not be seen and that someone would call me back to explain. Two weeks later, I called again and the same thing happened. Still no response from AF. I have emailed in asking for an explanation. Absolutely no response. I am fed up at this bad service. What do I need to do to get some answers?