Robert's Rules do not override your bylaws. In fact, most bylaws that specify a parliamentary authority such as Robert's Rules say something to the effect that Robert's Rules apply except when they conflict with the bylaws.

That said, there may not be a conflict between the bylaw you cite about special meetings and the RONR provision you mention about doubted vote outcomes. Was the election held during a meeting? If so, then the time to challenge the results was during that meeting. Otherwise, you may be stuck -- but you should amend your bylaws to allow some number or percentage of the membership to call a special meeting.

Our PTO recently held an election for the officers of next year's PTO. The current PTO president and VP violated 4 bylaws related to voting as well as a couple of Robert's Rules. In our bylaws, it is stated that the president (or 3 board members) are the only ones who may call a special meeting. BUT, Robert's Rules override bylaws. The Rules state that when the vote is doubted, any member can move to have the votes re-counted or thrown away. I sent out a lengthy e-mail specifying what bylaws/rules were violated and respectfully requested the president call a special meeting to address this. Others have made the request as well. Thus far, we have been ignored. What recourse do we have now?