I had something similar, a return CDG-JFK-PHL. AA cancelled JFK-PHL and rerouted me to CDG-JFK, SWF-PHL. Unable to get to a phone, I tweeted AA to see if I could get put on the non-stop CDG-PHL. No dice, since saver wasn't available. When I got a chance to call, the agent seemed surprised by such a connection (and the thought of changing JFK to SWF) and put me on the direct. They should be certainly be able to put you on an easier flight (or even reroute through another AA city such as PHL, ORD, CLT to LHR.