Relationships Aotearoa says desperate people could miss out on the counselling they need when the organisation moves its clients over to new providers.
The service is closing due to funding cuts and its 7000 clients are being transferred to five new agencies.
Today Relationships Aotearoa met with those picking up the work to discuss the transition.
Its strategic advisor Cary Hayward said they only had a couple of weeks to move their clients across.
But he said that was not enough time and to stop people missing out on services, they would have to identify the most high-risk clients and focus on their transition.
Mr Hayward said lower-risk clients may end up walking away from counselling services.
Social Development Minister said no counselling groups had approached her with concerns about vulnerable people missing out on therapy while the country's biggest provider shuts down.
Anne Tolley said that issue had not been raised with her, and it was best to let the agencies work through the transition themselves.
She said she thinks the new agencies would be able to do the work cheaper than Relationships Aotearoa.