You can choose to be notified when your account balance reaches a specified threshold
Log into https://live.2talk.co.nz
Select Manage Billing
Enter the $ amount for your balance threshold
Tick Enable Low Credit warnings
Click Save to save settings
When your account balance reaches the threshold an email will be sent to the email on the account.
You can use Auto Top Up to automatically add credit via a stored credit card if choose and Auto Debit to have your monthly fixed fees automatically charged to your account.