The Problem Gambling Foundation is going to the High Court tomorrow to challenge the loss of most of its funding.
The foundation lost the contract for the lion's share of its services in March, when the Ministry of Health awarded funding to the Salvation Army after a tender process.
Foundation chief executive Graeme Ramsay wants the process reexamined.
"We think that we deliver very, very high quality services and if the process that we've been through didn't recognise that and didn't recognise that we've been doing that well and delivering on our contract for 25 years, then there's something wrong with the process."
Mr Ramsay said the ministry told him the decision was not about price or performance, so he is not sure what it was based on.