Unfortunately I've run into the same problem with my Kobo purchase. I picked it up in store (in an attempt to continue supporting my local Chapters) but never did receive a coupon.
I've been in touch with Kobo support, and while being very friendly and quick to respond, they really haven't been able to help. My support ticket was then "elevated" to Level 2, two weeks ago and that was the last I heard of it.
I absolutely love my Kobo Wi-Fi, and am in no way soured because of this, but its just a bit disappointing. I was hoping to be reading Oryx and Crake by now. Hope it all gets sorted out soon.