Originally Posted by jennyb10

Thank you everyone for your help. I had a couple of exchanges with the customer service rep, which was a patronizing exchange of "we care about you, yadda yadda yadda" but refused to to credit me any miles back, as this was not their "policy".

I went on Twitter and they asked me to PM them. They couldn't help with past flight issues but told me to call a separate Customer Care number which I did. The woman there was able to get me just under 30k miles back, which was fair for the segment my parents were downgraded. My parents also have the option to trade in the flight vouchers for non-Delta gift certificates to several different stores.

Although it took much more effort than it should have, happy with the result. Thanks everyone.