This is, I believe, a provincial matter and I am not sure there is anything out there. The closest thing I can think of would be the Alberta Fair Trade Act, however I don't believe there is an overriding buyers remorse portion - only if she signed it under certain situations, that are deemed unfair, does it kick in.
Ontario has a buyers remorse act, but I think you may be SOL in Alberta for a general equivalent.
You could tell them she was drunk and unfit to sign a contract
