Wilson Parking New Zealand business manager operations Ryan Orchard said the business was unaware of the investigation. The commission said it had informed the company of its probe.
Mr Orchard said he understood there may be a pending investigation into a division of its business, Parking Enforcement Services.
"Wilson has not been formally notified of an investigation as you are suggesting," he told the Herald. "Accordingly, as I have mentioned, we have no comments to make."
The Commerce Commission said the new investigation was the only complaint laid against Wilson in recent times, and it was not clear how long it would take.
Its other investigation was launched in June 2013, when the parking giant purchased around 60 per cent of Auckland-based Tournament Parking's assets. That investigation is still considering if the acquisition will lessen competition in the industry.
Consumer Affairs Minister Craig Foss said he was waiting for an industry-led working group's assessment of the current Wheel Clamping Code of Conduct.
Wilson Parking came under fire from Herald readers last month for raising its charges at inner-city Auckland carparks while events were taking place.