Almost 1400 students voted in the referendums and the overwhelming majority supported two significant changes - the downsizing of the OUSA executive from 17 members to 10 and a move to conduct most OUSA consultation and decision-making online.
It was expected both changes would be introduced next year.
But OUSA general manager Stephen Alexander said yesterday the complaints meant the results were only provisional.
"Nothing is 100% sure until the complaints have been through their process."
That involved returning officer Donna Jones considering the complaints and deciding whether to uphold or dismiss them.
Complainants then had a right of appeal to an independent arbitrator.
The OUSA executive met on Friday, the day after voting closed, and appointed University of Otago law lecturer Prof Paul Roth as independent arbitrator, Mr Alexander said.
Ms Jones said yesterday the complaints process rules prohibited her from giving details of the complaints or her decisions on them until after the process was completed.
If implemented, the executive restructuring would result in the loss of direct representation for gay, Maori and Pacific students, and for each of the four university academic divisions.
But eight new committees would be established whose chairmen or women would be members of the executive.
A complainant who contacted the Otago Daily Times said most of the complaints were about a lack of proper consultation over the restructuring proposal.
The decision to go ahead with the referendums was made during the university mid-semester break when only 10 of the 17 executive members were present.
The complainant, who did not want to be named, believed executive members had not been given enough time to consult their constituents about the restructuring proposal and whether they should support it.
OUSA president Harriet Geoghegan said yesterday she was "a bit disappointed" at the complaints but they were expected.
They had been lodged by proposal opponents who were "clutching at straws" because their earlier attempts to stop the restructuring and referendums had failed.
She confirmed one of the complaints was that she was not impartial during the three and a-half day voting period and used social networking to encourage students to vote in favour of the proposals.
Ms Geoghegan acknowledged she had done that, but said she did not believe she had done anything wrong.
"I didn't see any problem with that.
"The OUSA executive supported the proposals and the decision to hold the referendums.
"If we didn't support the proposals, no-one else would."
Whether she was in the wrong "depended on interpretation", she said, and she would await the decision of the returning officer or independent arbitrator.
The executive had taken legal advice on the referendum process throughout and Ms Geoghegan said she was confident the complaints would be dismissed.
"We have worked hard to ensure a fair and proper process.
"I am sure that is what the returning officer will conclude, too."
