The authority said Mr Moore had persistently clarified these details with TVNZ prior to the broadcast.
In its response, TVNZ said the focus of the item was that members could not cancel their gym contracts despite a change in location, contrary to Fair Go's legal advice on the issue.
TVNZ was aware of the two women's individual circumstances, but maintained their comments were still relevant to the overall focus of the story.
The authority said the women's comments added to the overall negative impression of the gym, and the program did not fairly present any balancing comment.
"As TVNZ was aware of the facts and could have removed the women's comments at editing, or included a clarification at the end of the item, we consider that reasonable efforts were not made by TVNZ to ensure the item did not mislead."
The authority said the overall programme had a legitimate public interest, and publication of the decision was sufficient to remedy the breach.
A spokeswoman for TVNZ said they accepted the authority's decision but did not agree with it. She noted the authority did not consider it serious enough to warrant further penalty than publishing the decision.