Go-Bus CEO Calum Haslop said they operated servies in the South Island under contract for NakedBus.
"We operate Christchurch-Queenstown, Christchurch-Dunedin and Invercargill services for them and we were assured at the time of the purchase of that business by Mana that the old company would meet all its obligations and pay all its outstanding accounts, and it hasn't done so.
"We don't have any issue with the current ownership - we're continuing to operate those services on behalf of the new company, but the old company simply hasn't paid us."
The alleged outstanding debt was approximately $100,000, Haslop said.
"We feel we've exhausted all the [other] options at this stage.
"I mean, this has been going on since May and we're just concerned about the fact that we're not getting any meaningful response or any meaningful dialogue with the old entity or the old owner."
ManaBus.com launched last October offering long-distance, low-cost bus services on tourist routes through the North Island.
Comment was being sought from Nuttall.