I would think so but only if you connect to a hotspot close by you, which is my next point is why not bill share, It is much cheaper :) But you see the Wifi user list but you have to do your homework and unless you know their hot spot nickname :( but you must make sure that Koodo is not already connecting you via their web plan!
I'm assuming you're a prepaid customer, Eunhee. Unfortunately, there are no refunds once a payment is processed. The system will hold the money in your account. You can either save the $15 in your account, or apply the funds toward a talk or data booster. You can register for automatic top-up at any time, there is no fee for this.