The summer of shareholder unrest looks set to continue at the annual general meeting of Vodafone on 27 July with institutional investor, Ontario Teachers' Pension Plan (OTPP) set to vote against the re-election of the chairman and deputy chairman to the board of the world's biggest mobile phone network operator.OTPP, which owns around 0.42% of the total Vodafone shares in issue and is best known as the company that acquired UK national lottery operator Camelot, is unhappy with the structure and the strategy of the company and believes that the composition of the board needs to be rejuvenated.While it intends to oppose the re-election of non-executive chairman John Bond and his deputy, John Buchanan, the pension fund is supportive of chief executive Vittorio Colao, who has been in the role since July 2008."We believe the chief executive has begun improving Vodafone's operating performance and competitiveness," the investment group said.