"We are aware of similar concerns being raised across the Waikato DHB area by a range of providers, patients and clinician groups," Pinnacle Incorporated chairman Dr Frank Cullen wrote.
Pinnacle is so desperate to change the situation it is considering triggering a contractual dispute to force the relationship problems into the open, Cullen wrote.
He said Pinnacle raised concerns on a range of issues with the ministry a number of times during the past two years, both in writing and in person.
A mediation between the two organisations earlier this year had not resolved the situation and there had been "no change in behaviour from the DHB".
The letter accuses Waikato DHB of:
• Signalling its desire to exit an existing regional alliance between Pinnacle and the four Midland region DHBs
• Threatening withdrawal of flexible funding to the organisation
• Continued investment in virtual health system SmartHealth, including free access to after-hours doctors in direct competition with its contracted primary care providers
• Provocative gaming between primary health organisations in the region
• Keeping Pinnacle and other groups from the board.
"The contrast between our relationship with Waikato DHB and with the other DHBs in the Midlands Alliance [Lakes, Taranaki and Tairawhiti] could not be more striking," Cullen wrote.
He added that Pinnacle did not have any engagement with the board under the current administration.
"We have very little confidence in the current chair and the senior leadership at the DHB. Our concern for the population of the region continues to grow as performance and relationships become more strained.
"We do not expect we will be able to change the relationship without a major change on the part of the DHB or without third party intervention."
The letter follows calls last week for Simcock to resign if Murray is found to have inappropriately spent taxpayer money and echoes concerns raised by senior doctor representatives about Murray before he was hired.
Murray declined to comment and Simcock said he had not seen the letter.
"We are currently reviewing several formal alliances that the DHB is part of in order to find a solution that best works for everyone and involves all primary care organisations not just one PHO," Simcock said.
"We need to ensure all our community has effective access to healthcare outside of a hospital setting. Pinnacle has never been refused access to our board and we are always very happy to meet with their board."
Ministry of Health director of service commissioning Jill Lane confirmed receipt of the letter and said the director-general was considering it and would respond directly to Pinnacle.
"The ministry was involved in facilitating mediation earlier in 2017," Lane said.
"Following on from that process, the ministry has expected the parties to continue working together to promote good relationships in the interests of better health outcomes for people in Waikato."
The office for Health Minister Dr Jonathan Coleman referred questions to the Ministry of Health.
