This all depends on the terms of your purchase.
Some accommodation bookings are refundable, others have no cancellation affixed to them at the time of the booking - you will see this during the booking process.
All Activity purchases can be cancelled up until 48 hours before the activity
Flights can rarely be cancelled, unless the cancellation happens same day as the booking
With Deals, unless you've redeemed the deal and it hasn't expired, we're able to refund it if you're unable to redeem it. If you've purchased an Accommodation deal, there's a 7 day guarantee, where if we can't fulfil your desired dates for booking we'll refund it in full.