Extremely unhelpful!! DISGUSTING

I was debited twice yet I only approved a payment once on my app , FNB did not help me at all , HOW does the banking approve the amount once but debit the account twice ??? that is *****ulent because I'm being told to fill out a form and pay R300 for a reversal , for a payment I DIDNT MAKE twice !!! FNB cannot even assist me with reversal.