Dont trust FNB Online banking

On Tuesday 4 April At 14:40 I phoned FNB to change an email address & phone number off my mom's account at FNB Online Banking. The email address & phone number are no longer in use due to cable theft. Since I run all her accounts and I am the signature holder on this account the computer does not allow me to. Phoning FNB did not help at all. They say yes you can transfer or close the bank account but you not allowed to change the email address or phone number. When I wanted to rate the lady service as poor she just put the phone down. How is this possible? Can FNB service be any worse?