The charity released a fresh statement on Wednesday afternoon
A County Armagh couple who raised £65,000 for the Ireland Air Ambulance (IAA) in memory of their dead son say they want the money returned to them.
This is until they are satisfied with how the charity is spending its money.
Peter and Helen Fearon said they were "very disappointed" to learn that the charity spent 90% of its donations in its first year on wages and overheads.
The charity has not said whether or not it is prepared to give back the money raised by the Fearons from Drumintee.
"Air Ambulance has been contacting its stakeholders to underline its continued commitment to securing the service for the region and explaining that the high start-up costs involved in establishing a charity are not unusual," said Dr Gwyn Beattie, clinical director at IAA on Wednesday afternoon.
"This was confirmed by the Charities Commission for Northern Ireland who yesterday confirmed that a 'charity may spend more on its set-up than it will do in later stages of its development and operation'.
"This afternoon Ireland Air Ambulance spoke with Peter and Helen Fearon who are generous benefactors to the charity and offered to meet them to discuss their concerns.
"Ireland Air Ambulance is in the process of appointing external consultants to review the operations of the charity and ensure the business model going forward is robust and best serves our aim of providing an air ambulance to serve the people."