Australians suffering medical conditions were conned into believing their lives were at risk by sales teams pretending to be medical professionals, the consumer watchdog says.

The Australian Competition and Consumer Commission has filed Federal Court proceedings against Miyagi, a Sydney-based health and wellbeing business.

Miyagi is accused of employing unqualified staff to pose as medical professionals and wrongfully sell health programs costing up to $7500.

"In my professional opinion, with your [disease], it's safe to say that you're at risk of things getting worse," sales staff allegedly told customers.

These employees were directed to use the same line of messaging to sell Miyagi's different health programs to more than 6000 Australians, the consumer watchdog said.

It argued this wrongfully represented Miyagi's sales team as medical professionals.

The company also faces allegations it used unfair terms and conditions and refused refunds to customers who requested to opt out of its programs.

"We are extremely concerned that consumers, including many with complex health conditions, signed up to Miyagi's program on a false premise," ACCC Commissioner Luke Woodward said in a statement on Tuesday.

"Many consumers were left significantly out of pocket as a result of Miyagi's alleged misrepresentations".

The accusations are claimed to have taken place between 2022 and 2025, when the company promoted free phone call consultations for different health programs on social media.

Applicants engaged with Miyagi's marketing campaign and completed a health survey before a sales employee subsequently called to provide their "professional opinion".

Sales employees allegedly voiced the same script to wrongfully sell health programs focused on heart disease, sleep apnoea, menopause, obesity and gut health, the consumer watchdog claimed.

The commission also alleged the Australians who received these calls were wrongfully told it was scientifically evident their lives were at risk of being cut short.

The marketed schemes sold programs that lasted between six and 18 months and aimed to improve health conditions.

Payments to enter the program had to be made up front or through a payment plan.

Miyagi founder and chief executive Shane Da Costa, is the individual accused alongside the company, Mr Woodward said.

Mr Da Costa is claimed to have approved the Miyagi's contract terms and the telephone scripts that sales staff used when seeking to sign up customers.

Miyagi offers programs currently operating in Australia under brand names such as Diabetes Wellness Australia, and Heart Smart Australia.

It previously offered programs under other brand names such as Healthy Gut Australia, Master Menopause Australia, and Defeat Sleep Apnoea.

Miyagi has been contacted for comment.