What is the purpose of FNB peronal bankers

A week ago I received about 7 emails stating that my personal banker was changed again (the 2nd time this year). Today when I needed FNB's assistance with a card dispute, the banker is unreachable (just like all the other times when I tried calling any of the FNB bankers allocated to my profile). Why so many changes FNB, and why do you provide such poor service? Just don't bother allocating anobody to me because I have to contend with your call center staff in any case.