I would we cannot see the condition of your phone. So if you assume theres a dent or crack I'd suggest exchanging it while you're under your 15 day grace period. Otherwise, you'd have to call apple tech support.
As far as my understanding, Koodo doesn't provide extended warranty for specifically the otterbox but I may be wrong on this one. were you provided any paperwork to justify this?or do you have anything on hand to present to the store if need be?
How about my phone, will they do something I had it less than a month it's in the otter box case with screen protector, and I just noticed there's something under the screen, not under the screen protector. Under the actual screen