In post #3, the poster noted: "It's of course based on what you
paid."
I'm confused, especially if I'm flying on a DL Vacation package, where the price I
paid is not known to DL [which is why MQDs are Distance based for DL Vacs.]
The issue is you have a BULK ticket. This is not a ticket you can call DL and make voluntary changes to. They can rebook you if they make a schedule change, but cant do it for voluntary changes. This is why I commented about DLV and BULK fares in my earlier post.
What you're posting about only applies when doing published fares not BULK tickets.
Note DLV can and does also sell published fares. However if you're buying with hotel and the fare is lower than what's available on DL.com, you likely have a BULK fare.