Medication was delivered to his home despite Mr D never receiving a required consultation with a local doctor.
He then discovered his credit card had been billed $2880 on the day of the original call from Australia without his consent.
Repeated calls for a refund were refused. His bank reversed the charge about two months after it was levied.
Another man, known as Mr C, was recommended a 12-month treatment programme over the phone from Australia in November 2007.
His credit card was charged an initial deposit of $1200, though he did not consent to the programme.
On January 1, 2008, Mr C wrote to the Advanced Medical Institute asking for a refund but did not receive a reply.
The company only refunded the money in full after receiving a call from the HDC nearly 18 months later.
The HDC also reprimanded a New Zealand doctor for prescribing an injectable medication without conducting an adequate physical examination.
Another was censured for failing to carry out a proper physical examination, obtain a full medical history or advise a patient about alternative treatment options before prescribing medication.
The HDC report said the Advanced Medical Institute had provided a poor standard of care to all four complainants.
Its convoluted and ineffective complaints process was "unethical and unreasonable", the HDC report said.
All four doctors involved in the complainants care were ordered to apologise.
The HDC recommended the institute overhaul its New Zealand operations, including the training delivered to its contractors and the amount of information on offer to patients.
