Welcome to the Bunnings Workshop community. It's marvellous to have you join us, and thank you for sharing your question about repairing your damaged wall.
Would it be possible for you to step back and take several photos of the entire wall including the post? Putting new render on your wall is not that difficult, but finding out why your wall tilted is another matter. It would be a shame to repair the wall and it moves again.
I propose finding the cause of the movement first before you make repairs. It might be due to poor drainage from you or your neighbour's garden. It could be poor foundation prepared by the installer. Whatever the cause it must be first addressed before repairs are carried out.