How and from whom was the itineraries purchased? Did you have one or two "TICKETS" .

If you bought one ticket YYZ ATL SAV it would be trip invain due to DL unable to fly you there and you should get a full refund. Seems like you were ticketed somehow as two as the ATL SAV Cancellation had no bearing on th YYZ ATL flight.

I had many trips fully refunded due to "trip in vain" .

DL DM from YYZ