Can you check self serve to see if those calls were made using the phone line instead of Whatsapp? That is usually what happened when charged for minutes...

@pierreb If the calls appear on your invoice (which it seems) than they were made though regular calls. WhatsApp calls would only show up as data since that is what makes the connection possible. 

That makes no sense.  WhatsApp is an encrypted service over the internet.  Koodo would have no way of knowing where you called...unless you made the calls over the phone network instead.