Credit Card - Unauthorized Transaction

I noticed when working through my account, notifications of transactions on my credit card account, that happened without my authorization. Immediately phoned Nedbank to stop my card. Then queried whether they can stop the transaction and recover the money. Call centre agent logged a dispute. When asked for a reference number, he wouldn't provide one. Stated, I needed to visit a branch. Visited the branch the next morning to report the transaction. I received a email the following day, stating bluntly I will be liable for the transactions, they cannot help. Rep**** on the email with questions but without a response. I did not make those transactions with the merchant. I informed the merchant of this activity on my account. Changedwell as email addresses all my passwords at the merchant as . Still haven't heard back from the merchant. Thing is, with all online payments the page will redirect, it will ask for SureCheck popup or an SMS code which you need to approve, giving authorization. There were none of these. Why not? Also, I never "gave" my credit card details to the merchant? I have transacted with them before but no where did I give consent? I would like for the transactions to be stopped or reversed or any way to recover the money? Please urgently assist with the matter.