Tough question. The difficulty really is (IMO) that the carrier could be on the hook if they allow her to board and she is inadmissible i.e. she is more beholden to the airline than anyone! I am also not convinced that a visit to the visa office gets it sorted, since they will defer to Ottawa.

My suggestion is you look for a contact us icon in the WEB site for the eTA. Its likely to be quicker and more effective than other alternatives.