Gemma Merritt said she had been dying to get a Fitbit for ages when she finally bought one in 2015.

"I thought, 'I’ll splash out with my birthday money and get it'," she said.

"Looking back now I wish I hadn't bought a Fitbit."

Gemma Merritt is one of more than 100 people who complained about Fitbit to the ACCC.

After about seven months, Ms Merritt said the band snapped. The company replaced it, and then replaced a second when the same problem occurred. But when her third replacement broke after less than a year, in October 2016, she said the company would not help.