Failure of service

I am writing on this platform to voice my frustration of the bad service at FNB. I have asked for credit card manager to call me for two weeks now and I am still waiting. I wrote a letter 26 June and only received feedback 16 July, and this again affected my finances. They were supposed to reverse a payment and to date it hasn't been done. They promise personalized interest rates, but they offered me 23% and my account is already in arears whereby the arrangements was not managed according to what I was advised. My own bank is giving me a bad name, and I am a private banker