shocking and poor service

I have been dealing with FNB dispute department for over a month now regarding the transaction which i am disputing on my account. It is been a back and forth communication without getting any solution, Which they keep on saying i must send them the communication between me and the mecharndise. How am i going to communicate with them if i have never dealed with them. This is shocking statement from FNB dispute department. It so sad not to get help from the bank you banking with and paying the charges for them to help you when you need help.