Looks like this deal is back again:
https://www.ozbargain.com.au/node/377674
To claim your reward, join an eligible Medibank combined Hospital and Extras cover, enter the promo code 'REFER' and provide your 10 digits unique referral code when you join. Your referral code should be 10 digits long.
Get 6 weeks free cover (freebie obtained after staying with Medibank for 6 weeks initially) by quoting "REFER" followed by a 10 digit referral code.
If you have a friend who is already a member, you can ask for their referral code instead. Referrer gets $100 after the referee stays a member for one month. Maximum 5 successful referrals per calendar year.
Terms and conditions: https://www.medibank.com.au/livebetter/refer-a-friend-progra…
General advice only: As far as I'm aware, this is one of the better value sign-up deals in the Health Insurance space. Some providers offer a $200 gift card or Flybuys points to that amount for family cover, however 6 weeks free is likely to far exceed this in value, particularly if you are looking at a higher level of hospital and extras cover. As always, YMMV, so be sure to shop around like a true OzBargainer!
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To use a referral code, append the referral code after the coupon code. Eg.
REFER{Referralcodeexample}
does this work for Extra's only as well?