I called optus today to complain about not being able to contact them on the app and they suggested i uninstall and reinstall it - still doesn't work, then I went into the store to try and get help, they have no idea. This is supposed to be the way to communicate with them and you can't even communicate with them, it's beyond frustrating.
Please see My Optus app troubleshooting tips. ,artshopz.
If still no luck, as it says at the end, please contact the Social Media team for assistance.