Normally if the seller is excellent they will send you another item and then the seller will claim the money off Royal Mail.
Or even in some circumstances I've had a full refund and a replacement but this was for stuff not too overly expensive.
Yesterday I had three small packages dropped through my letterbox and they was not even my name or address,
I chased the postman and then bollocked him telling him can you read, he then pulled out his ear plugs :roll: