The Optus $2 Days Pre-paid plan is a unique and surprisingly generous option for anyone who uses their phones a lot some days, and not at all on other days. For the titular $2 nugget you get unlimited calls and messages, plus 500MB data to use in a day.
This system can really work in the favour of someone who knows how to monitor their usage, but the problem that most people will find is that, even though they may not make any calls or send messages, their phones will automatically seek internet data each day, and this will deduct $2 from your credit from the moment the first bits got through.
To get around this, you can set up your phone to only seek data when you tell it to. Here’s how:
Android
Different models offer different ways to achieve this; some easy and some laborious. If you have a Samsung or an LG you will find a ‘Sync’ button in the Quick Settings across the top of the Notifications window — toggle this to off to stop your phone from auto syncing data.

Sony phones have a Settings widget that you can install on a home screen with a similar button.
Otherwise, the process takes a bit longer.
1. Go to Settings > Accounts
2. Select each account listed and uncheck each of the sync options for these accounts
iOS 7
With iPhones and iPads running iOS 7 there are a few places you need to stop into.
Background App Refresh
This option is found under the ‘General’ pane of the Settings app and controls how some apps will automatically update while in the background.
To make the best use of your credit, you should turn this setting off.
Auto App Updating
This is an iTunes app setting that is designed to keep apps and music downloads up to date. Happily, you don’t have to turn this useful setting off, you just need to make sure that the ‘Use Mobile Data’ option is left unchecked.
Check out other Unlimited SIM-only plans here
Joseph Hanlon