Charging me fees for your mistake

On the 31/03/18 I made a purchase of roughly R2500 which left a further R1500 in my account, leaving me enough money for what I needed to do on that day. However I was double charged the R2500 by Nedbank, which put my account in negative. I made 2 more purchases that day, of which one was AGAIN double charged. This meant that FOUR transactions took place while my account was in negative because of a mistake from Nedbank. I was charged 4 x R90 HonFee for being in arrears. Nedbank reversed the double charges of R2500 and R400, which put my account back to a positive balance, yet they didn't reverse the R360 in fees due to what was clearly an error from their side. I am currently overseas with no way of coming it to dispute this and after a half hour INTERNATIONAL phone call I have recieved no help whatsoever. You cannot charge me fees for your mistake and then insist I come in to discuss it, this should automatically be fixed and the money credited back to my account without me having to make international phone calls and write on here.