The entry of company 2degrees into the mobile telecommunications market last year appeared to take a bigger toll on Vodafone than rival incumbent Telecom.
The Dunedin City Council is switching to Vodafone for its landline and cellular calls.
Vodafone has apologised to Bay of Plenty customers affected by a network failure on Saturday.
The Commerce Commission, in a split decision, has rejected regulation as a means to reduce the costs of mobile phone calls.
The Commerce Commission has closed an investigation into a potential breach of a confidential interconnection agreement between mobile phone operators 2degrees and Vodafone in stories in the Independent and the National Business Review newspapers in August.