I have referred a friend (here in Aus) four times over the last 48 hours or so, and he hasn't received a code bearing email from Kobo.
I dare to suggest that the codes are no longer being sent - even though the referral screen still shows at the completion of a book buying transaction and when you follow the referral instructions confirms that your friend will receive the code bearing email within 48 hours. Nope!!
Today is the 13th (in Aus already) and the Refer codes were proposed to be stopped either by the 13th or on the 13th depending on how you read the promo.
However, the code bearing emails state that the code is good at the checkout until the 20th ..... so let's hope that is still correct, eh!!
BTW, I've tested a code and it still works this morning.