Mainfreight wants KiwiRail to stop giving preferential freight rates to Toll Holdings.
Toll New Zealand was given a freight discount when the company sold the rail business back to the Government last year. It was supposed to expire three months ago.
KiwiRail is now owned by the Government.
KiwiRail says a pricing policy is being developed and commercial negotiations are seldom finalised overnight.
Mainfreight managing director Don Braid told Morning Report he would like to see the discounted rates end immediately.
He said six months should have been more than enough to work out a new deal.
