Who Deals With Complaints

I have been experiencing problems with a branch of Trust Services. I contacted FNB Trust Services Customer Centre On the 12 November 2014. I spoke to Mrs Benadie. I sent her the relevant emails and she promised to get back to me with a reference number. I had no response, and sent a follow up email to Mrs Benadie on the 4 December 2014, requesting the reference number, the Names, Positional Titles, and Contact Details of the Head of FNB Trust Services, the Head of FNB Wealth and any other relevant mangers at FirstRand Bank. This email has also been ignored. I would like to know who I can deal with, that is superior to the Regional Manager. Every time I call FNB Trust Services they cannot give me the name of any one more senior than the Regional Manager.