I just had a rep in the process of changing the date for my return on an award ticket tell me that the ticket was non-refundable.

My assumption was that under the current rules if I wanted a refund I could get a refund of the miles attributable to the return portion of the ticket. So, e.g., if I had a RT ticket to AMS for 70K miles (fared based on 35K each way), if I didn't take the return flight I could refund it for 35K miles.

Was I correct or the rep correct?

(somewhat contradicting what she said, I had contacted Delta to change the return date on a half-flown ticket, and the reissuance caused me to be refunded 5K miles as the alternative flight cost was 5K less than what I had originally booked.)