FNB changed my name??????

Somehow, my last name (surname) has been changed on my banking app. My online profile still reflects my correct name, but I am now unable to access specific services which are in fact the entire reason why I am still with FNB (MoneyGram) because my name is now different. This change happened over the holidays and the app will not allow me to correct the name, stating that this is the detail from home affairs, which is entirely impossible as home affairs does not do name changes over the holidays (not to mention the fact that my name should not have been changed and there is nothing to indicate that it has been changed at home affairs). I have had 3 separate interactions with FNB regarding this, they say that their side reflects my correct surname and they are unable to assist me. Useless.