Don't bother with the phone. Write a quick email (specifics only, no emotion), use the complaint form on Delta.com and wait for their reply.

I don't know for sure, but I think the phone reps are limited in what they can offer.

FWIW, I had a HKG-DTW-RDU itinerary changed to HKG-NRT-HNL-LAX-RDU because of two mechanical problems (HKG-DTW and HKG-NRT) arriving 15 hours late and I was automatically given 10,000 SkyMiles. I didn't ask for more. I was a PM at the time.