Hi Jane,
depending on the country you are shipping to, the shipping, customs, and delivery can take from 2 weeks to 6 weeks.
I would write to the customer and firmly but kindly inform them that international shipping is more time consuming than domestic, and that, if he decides not to accept the parcel, you will refund him:
WHEN you receive the parcel back.
stand your ground though, offer the tracking info -
but the threat about not buying from you again, just let that stuff
go.