I have already used the Atlanta to London portion and now I would like to use the return portion only as far as Toronto. (therefore no worries with out of sequence ticketing).
I changed contracts since Atlanta and as such so have my travel patterns. The ticket is a deep discount consolidated ticket ($258 USD return). Route is not changeable.
Yes, the tickets to the US are cheaper than to Toronto with Air Canada. Ironically, tickets to Montreal and Halifax can be bought here in London with a stopover in Toronto at no extra charge and the airfare is the same. So anyone flying from London to Toronto may want to consider flying to a further destination. US points require 7 day stay.