I know she could vote but we didn't know that it is according to her last address. This makes sense.To be clear: for ages now, Canadians living abroad have been able to vote. I did it when I was abroad, and you vote according to the 'most recent' place of residence in Canada (if I remember correctly).
Your spouse - the citizen at any rate - should write and make it very clear to that MP that the attitude to citizens abroad of their staff is costing them votes.
We contacted David McGuinty office (people should know their "heroes" ) since he is the MP for where my wife's sister lives and it is going to be our temporary residence for some time before we settle.
The office response was blunt and dismissive.
We explained everything and they went like " your family members who live here already can request anything, you cannot".
But thank you for advise we will contact the MP from her prev residence.