you can try login to your M1 account and recontract.How to get the recontract offer? I'm still using 500mbps, contract over but didn't receive any offers.
if you are entitled for the offer, no need to key in any redeem code, it will be there for you to choose
$13 for 10gpbs
$15 for 6 gpbs
choose the relevant one and select "Apply"
