FNB I want my refund incorrectly debited

I am totally disappointed with my bank FNB,I was debited of which I requested for the debit to go off on the 1st of November.I took a sim only deal through connect, different consultant are calling me but when I tell them my story and that I want a refund no one seems to care,I'm really angry and disappointed at fnb.Im actually thinking of leaving FNB.