The sender pays for sending a package.
Any cancelled items would be returned to the pickup location.
After pickup, if the item is cancelled before arriving at the recipients location there will be no additional charge to return the item. (Unless it was sent to Tobago - All cancelled Tobago items will incur the usual delivery fee)
Also, if the item was cancelled after the driver arrived at the recipients location then there will be a charge to return the item to the sender.