A family's grief at losing their mother has been compounded by a courier driver's error that has left the whereabouts of her ashes unknown.

Perth-based Nelsonian Brett Smith's mother died in Greymouth in August.

Following her funeral and cremation, a portion of her ashes was put aside to be made into a piece of jewellery for Smith's niece, as a keepsake to remember "Granny".

Supplied A missing portion of ashes belonging to Brett Smith's mother, pictured, have disappeared after a courier driver delivered to the wrong address.

"Before mum died she bought a pandora bracelet charm for her granddaughter - it was her wish to put a bit of ash into a bead for her, so when she wore the bracelet she can be with her, basically."

The family arranged for the ashes to be sent to a company in Nelson who makes the jewellery.

However, the company charged with getting the ashes to Nelson - Fastway Couriers - sent the package to the wrong address.

Fastway Couriers has apologised to the Smith family for the loss of a portion of their mother's ashes.

"The driver decided that as the package was a PO Box that he thought he knew the owner's home address and decided to deliver it there - even though I understand it was signature required," Smith said.

"They tried to go back for over a week to retrieve it, to no avail."

The situation had caused a lot of additional stress for the family, made worse by Smith having to resolve the matter from Western Australia.

GEORGE HEARD/STUFF Brett Smith's mother was cremated in Greymouth before a portion of ashes was sent to Nelson and delivered to the wrong address.

"Packages go missing all the time but just happened that the contents was a bit of mum, so makes it a bit different and the fact it was the driver who made a mistake and admitted it," he said.

"Part of her is in some stranger's bin or in the gutter, all because they screwed up."

Smith had been contacted by the general manager and chief executive of Fastway to apologise for the mistake. The company had sent flowers and offered $90 in compensation.

Smith said accountability, not money, was what the family wanted in order to move on.

﻿"Mum was only 52 when she died, and now there's this to deal with – if it's been destroyed or if they've thrown it away, just tell me, then I can close the book on this."

Speaking on Friday, Fastway general manager franchisees Adam Greer said the company deeply regretted what had happened.

"Since the local franchise was alerted that the parcel had not been received, they have done everything possible to find it. Both the regional franchise owner and the courier franchisee have made numerous attempts to locate and retrieve the parcel with no success."

A full explanation had been provided to all parties involved, as well as an apology to the family.

"We have also been supporting our courier driver during this very difficult and sensitive situation and will continue to do so. This has also included providing the driver with some retraining. The wellbeing of our team is also important to us and we recognise that people can make mistakes."

"Out of respect for all family members and our courier driver we will not be making any further comment through the media. We welcome any information from the public that could lead to locating the parcel."