A simple fix for dirty tricks?

There is perhaps a reasonably effective way to stop the kind of dirty tricks we saw in Irwin Cotler's riding (referenced in a couple of earlier posts): 

Canada has a do-not-call list, so that we can opt out of being on the receiving end of pesky sales phones calls. Political parties, polling firms (and  media outlets, by the way)  are exempt from the legislation, because it's assumed that their phone activities  have   a public-service component. 

Why not just amend the legislation, so that if any of those   entitities are found to be bending the truth, using the calls to harass or mislead people, that they lose their public-service exemption? As regular readers of this blog know, I also think that political parties should voluntarily adhere to the code of Advertising Standards Canada -- the one that governs the private sector.  It simply isn't sensible, in this day and age, for  politicians to be getting away with lower standards than banks or corporations or small businesses -- especially when it's masked as public service.