The letter from Sensis expresses "concern" with the way OZtion has been communicating it's free listings service for all customers who use their website.
OZtion founder Phil Druce said he was mystified by the demands, considering Sensis' own website promotes exactly the same thing.
"The terms OZtion uses, ?Free to list items' and ?You can list items for sale on OZtion for FREE', are fact." Druce said.
"A quick review of a Sensis online auction site, The Trading Post, sees virtually the same terminology, and certainly the same meaning, used in a similar way when promoting their own services."
Sensis's letter quotes several areas in the Trades Practices Act 1974 that they believe are being broken, seemingly unaware that those same rules apply to them, and therefore if their accusations were correct they would be guilty of the same breaches.
"Their letter simply doesn't have merit, as our statements are correct and you can list items for sale on OZtion for free", Druce notes.