***** unauthorized transaction

I have been the client with FNB for years now and this morning I woke up with a text saying there's a reserved R479.88 Transaction from StudoCucom that I know nothing of and never authorized. I then logged into my chats to speak to one of the consultants by the name Of Khanyisile and confirmed the name of the transaction but failed to give me full details. She said it was an online transaction but could not assist further kept on referring and also canceled my checque card without confirmation from myself. If FNB is not going to assist thier clients with such ***** then this means we must move to other banks