again, you need to file 261. The way to do this is via the complaint/compliments page on DL. You will just be wasting your time and that of the agents in the SC.

The fact that your ticket was again reissued into OY gives further support to the whole issue that you were upgraded then downgraded. It’s not incumbent on you as a rank and file passenger to understand why. Just tell them succinctly what happened and ask for downgrade comp aligned with 261 rules. I’ll bet you get it. And if you don't, you should at least get a much more clear explanation of what is going on and probably a lot more than 10K miles.