Can we cancel a flight within 24 hours of booking but less than 7 days before departure and be refunded

We had to buy tickets with air transat after missing a flight due to a delayed connection. Afterward, we were offered a free flight back home by one of the two companies we were traveling with. Can we cancel our airtransst flight? The form online says it needs to be within 7 days of departure but ours is tomorrow and we can’t reach them by phone