I'm in a similar position for flights in September. The email says that they will be in touch with me, and for the time being I'm prepared to wait to see if/when they do, rather than potentially sit around waiting on the phone. Assuming that your journey is on a single booking with one PNR, then I'm pretty certain that only one part needs to be cancelled for the whole reservation to become refundable...and that is what I will be doing.