Refusal to reverse a transaction

I have requested a transaction to be reversed on mu credit card more than a week ago, I have sent emails, phoned, cancelled my card and FNB still has not reversed the transaction. The keep referring me to ***** but that department doesn't even get back to me regarding the matter, no one is assisting. With my ABSA account, a debit order went off wrong, I phoned and the transaction was reversed immediately where with FNB they just ignore the clients. I want that transaction reversed immediately!