FNB Customer Service from Private Banker non-existent

I have a transaction that was declined in error on the 30 April as the InContact showed immediately that the funds were debited from my account. I paid the Merchant in cash and have submitted the cash receipt in support of the debit being reversed on my credit card. This has still not happened two months later. My Private Banker wants confirmation from the merchant in Nigeria that the dispute was resolved. I do not understand how the dispute lies with the merchant as they have been paid. I am being inconvenienced as your client and find this customer service unacceptable. I call in once a week for feedback as my Private Banker is not addressing the issue. Is it acceptable for me to still be chasing FNB after two months with no resolution in sight?