Credit to @WatchNerd
This can last 3 months if combined with $20 referral credit & activated on the $29 (25GB) plan. So $45 + $20 equals $65 credit.
1st month $29 (25GB) - 2nd month $19 (5GB) - 3rd month $19 (5GB)
Once your account is set up you can move to the $19 (5GB) plan so it's ready for the next payment date, $2 more needed for the 3rd month. Belong Plans(dam.belong.com.au)
Before you activate make sure you get a referral code from a friend already with Belong or the OzBargain referral randomiser for an additional $20 credit. If you've been with Belong before you will have to use a new email in order to get the referral credit again.
Unlimited national calls & sms.
Unlimited data banking & gifting.
No lock-in contracts.
Flexibility to change plans once every monthly payment cycle.
Data slows to 1Mbps if you use all your monthly allowance.
Telstra
12 month starter pack expiry (you have 12 months from the purchase date to activate)
Limit 2 per customer.
Never tried it, but maybe you could try asking JB's online chat for a price match (e.g. https://www.ozbargain.com.au/node/850716) and then use a perks voucher at checkout?