FED up with constant delays on his regular trips to country NSW, cardiologist Charles Thorburn fired off a letter to regional airline Rex to express his concern about the deterioration of its service.

The airline's "offensive and arrogant" response was not what the doctor ordered.

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Dr Thorburn was dumbstruck when, in response to his complaint, Regional Express - which is majority owned by a group of wealthy Singapore investors - questioned whether he would reimburse patients "who did not get well after seeing you".

The letter, sent by Rex's corporate services general manager Irwin Tan on behalf of company chairman Lim Kim Hai, went on to say: "Perhaps in the medical profession you are used to dispensing information on how long you make your patients wait or how often you misdiagnosed."

Yesterday, Dr Thorburn said he was outraged by the airline's sarcastic response to his genuine concerns.

"I didn't ask for reimbursement. I expected a letter of apology and I wouldn't have taken it any further," he said.

The Sydney cardiologist has been travelling to Griffith every two months for more than 20 years to meet about 50 heart patients in one day.

He makes the journey to check patients' defibrillators and pacemakers so the community doesn't have to travel nearly 600km to the city.

Dr Thorburn raised his concerns with the airline after he had been late to his patients on a number of occasions due to the airline having flight problems. The latest incident involved being bussed to the nearby town of Narrandera after the plane needed urgent repairs.

He and 28 other passengers had to wait for four hours. During that time they were offered just three pizzas between them.

"This is the second time in a year where the flight back to Sydney has been cancelled with no notice or follow-up," Dr Thorburn said.

"The irony is that at Griffith airport terminal check-in there is a Rex sign that says 'The heart of the country'. I'm a cardiologist who looks after hearts in the country."

The community of Griffith has rallied behind Dr Thorburn, with the town's Mayor Mike Neville saying what Rex had done to Dr Thorburn was unbelievable.

"The doctor provides a much-needed service to our town and he has been treated shabbily,'' Mr Neville said.

Infrastructure and Transport Minister Anthony Albanese said passengers were entitled to be treated fairly.

"This means having their complaints dealt with properly,'' Mr Albanese said.