NonprayingMantis: technically credit does not expire.
*however*, if you don't topup for a period of time (I think 12 months, cant remember, might be 6 months) then your account is deemed inactive and so deactivated and so?any remaining?credit balance?dissapears along with it.
this is the same principle for Vodafone and 2Degrees.
billgates: Once you have an online account set up with Telecom, then on the ipad you can save a bookmark under safari for the following address.
no need to log in with the above link. it displays your data usage, remaining data, plan details and you can even top up via the link using your credit card.
it's setup for a smartphone dize screen but looks and works fine on an ipad as well.