The group protesting against Government intervention on the price of the copper network says if new demands by Chorus are met it could cost New Zealanders $979 million.
The Coalition for Fair Internet Pricing had previously estimated the cost at $600 million.
Chorus made a submission on the proposal public after the Government proposed a discussion document to intervene on the price of the copper network.
Coalition spokesperson Sue Chetwin says after reading the submission it became clear Chorus is now asking for an immediate increase to the price of copper.
She says if that demand is met, the Government will effectively be giving the lines company a $979 million subsidy.
Chorus says the coalition is basing its figures on the wrong premises and they are misleading.
The lines company reiterates its stance that Government intervention is needed because the current regulatory framework is not appropriate for the transition to fibre.