@nikki19
Form 1023 won't work since you were actually referring to your state nomination application errors. I'm afraid you can't do anything about it, unless somebody here confirms they were able to update their details after paying the nomination fee.
This is in Immigration SA's <a href="https://www.migration.sa.gov.au/application-t-and-c">Terms and Conditions</a> during nomination application:
<blockquote class="Quote">After submitting your application by selecting the 'submit' button, your application will be locked and you will not be able to make any further changes
to your application.
Changes may only be made to the application before selecting the 'submit' button. Requests to 'unlock' a submitted application will be refused.</blockquote>
I think you should try to contact SA Immigration. Kaso wala akong email address nila. Meron silang "submit enquiry" tab don sa Skilled Migrant page mo, but tbh I'm not even sure if it works. I did submit an enquiry before but have gotten no response. They do have a phone line though T: +61 (8) 8303 2420.