The Prime Minister says he's yet to speak to Tau Henare about a driving incident involving the MP in which he was described as "abusive and degrading".
Auckland mum Cicelia Holliday told the Herald she was "absolutely gobsmacked" by the incident and wants Mr Henare to be called to account for his behaviour.
The complaint comes days after it was announced that the MP had dropped 14 places on National's general election party list.
Yesterday, Mrs Holliday emailed a written complaint to John Key and mailed a second letter to police national headquarters.
She said she was driving with her 12-year-old daughter along Ash St in Avondale just after 10.30am last Thursday when a car in the lane beside her suddenly pulled in front of her without indicating the lane change.
"I reacted by quickly blaring my horn to draw attention to the fact that they had created a 'near miss'," she wrote to Mr Key.
"I noticed the driver give me the finger though the driver's window and I couldn't quite believe it. Then he gave me the finger through the rear window with his left hand."
Mrs Holliday then noticed the red Audi stationwagon carried Mr Henare's name and photograph and the National Party logo.
When it moved back into the left lane, she passed it and saw the driver was Mr Henare.
Both drivers stopped at a red light, and Mrs Holliday said Mr Henare wound down his window and started to shout at her.
"He started going on about 'what happened to common courtesy' ... repeatedly talking over me when I tried to ask him why he hadn't indicated his intention to move across the lane in front of me.
"He shouted, 'Do you expect me to stop and let about 10 cars go past?' and I said, 'I expect you to indicate your intention to change lanes'."
The light turned green and Mr Henare drove away.
"I am a National Party supporter, but Mr Henare's behaviour was reprehensible, to say the least - both his driving and his finger-signing," Mrs Holliday wrote.
Mr Henare laughed when approached about the complaint, and refused to comment.
"I'm not going to respond to it, quite frankly, I'll just leave it," he said.
Mr Henare said he had seen the complaint and knew it had been sent to the police.
When told it had also been sent to the Prime Minister, he said: "The police are more important in this respect. I'm not going to deal with it through the media."
Mr Key today said he had not spoken to Mr Henare, but his office had.
"I understand he's disputing some of those details. The rest of it I'll leave to him."
Mrs Holliday said Mr Henare's actions were "absolutely shocking".
"What gives Mr Henare the idea that he is entitled to drive as he pleases? Does being a National MP and driving around in an Audi splashed with National Party colours entitle him to special treatment ... be rude to other road users, ignore road rules and endanger others on the road? Is he better and more important than others?"