Concerns had been raised in July last year and issues flared up the following month, leading to what has been described as "raised voices" and city councillors walking out of a meeting.
Dunedin Mayor Jules Radich asked councillors for their thoughts about what had happened at a meeting just for elected representatives on August 23 and Cr Christine Garey took the opportunity.
Several councillors witnessed Cr Vandervis "yet again behaving in an enraged manner, raising his voice very loudly", Cr Garey said in an August 27 email.
"Such was his behaviour a number of us got up and walked out."
His conduct made for an unsafe workplace and could not be "laughed off as ‘that’s just him’ or put down to ‘frustration’ or that it’s ‘just politics"’, Cr Garey said.
"His behaviour is way beyond that."
The mayor responded Cr Vandervis was one of the first people to move to leave the meeting.
"This was in response to being called a bigot by you or Cr [David] Benson-Pope.
"So, in the first instance, the use of inflammatory language could be considered a provocation and you and other colleagues need to take responsibility for that and desist."
Cr Garey replied she did not use the word bigot and she had been measured in what she said.
Mr Radich told Cr Garey he would not be taking any further action, but "you have the code of conduct at your disposal and may lodge a complaint if you so wish".
In the end, Cr Marie Laufiso lodged a complaint in November about Cr Vandervis and he was found to be in breach of the council’s code of conduct, including for an email he sent in July last year.
He has been asked to apologise to the council’s Te Pae Māori forum and to attend its meetings.
The cost of investigating the code breach was $11,680.
At the time she laid the complaint, Cr Laufiso told the mayor she would have preferred "that you had dealt with this matter without incurring the costs of an investigation".
"You have been asked multiple times, in writing and in person, to address concerns around the councillor’s behaviour," she said.
"These concerns have largely gone unacknowledged."
The mayor did not respond last night to a request for comment.
Cr Sophie Barker shared her own recollections in an email on August 28.
She got up to leave the meeting mainly because she had another meeting to get to, she said.
"The descent of the discussion provided a perfect moment to depart."
Cr Barker said there were "raised voices and I think I said something about name calling".
Personalities and politicking at sessions for elected members only had made her extremely uncomfortable in the past.
"I consider that we may want to rethink this process, as there is a long history of councillor clashes and this may be providing more fuel for them."