unauthorized deduction from merchant

Good day,

on the 21/11/2017 i made an online purchase on a site which was suppose to be a once off amount of R43. on the 26th of november the same company deducted an amount of R582 i immediately contacted FNB which requested me to fill in a form and mail to them which they will only get back to me after 5 working days. when they rep**** they wanted proof that i contacted the merchant. which i gave them and told them the merchant has not gotten back to me. after waiting days they rep**** and requested the proof of communicaiton in PDF. i than did so. the guy rep**** after a day requesting it again in PDF i than sent it again and till today i haven't heard anything from FNB and this morning again those guys **********ly deducted an amount of R582. i sent them communicaiton again from their website as they have no email adress. i know i will not hear back from them. and because FNB have been so reluctant and lack lustre in assisting me with a ********** transaction these guys just keep *****ing from me and FNB isnt doing anything! this is ***** and FNB should take it more serious. if this matter is not resolved within a week i will open a case with FNB and i will move to another bank