Refusing to tke dispute on credit card

I have logged a dispute on my credit card with Nedbank with a transaction for Eagle liner as I wasn't getting anywhere with getting my refund from them. The transaction was in error and no service received from the supplier for the amount. I made a transaction online and it first came through as an error online and later on the statement the transaction had gone through on my card. I logged a dispute with Nedbank to do a chargeback on my card as it is my right to dispute transaction when no service was rendered. Nedbank is telling me I don't have right to dispute a transaction, which is mainly laziness on their part. Please do your job and send the request to their bank for a chargeback.