Your posts says you asked them to credit to Dejta but you didn’t t say what the agent’s response was. I assume he or she said no problem we can do that here’s your boarding pass?
And now they’re basically saying the agent screwed up and shouldn’t have told you that? But they can’t compensate you on Delta miles for that error.
What I find odd is them saying it’s “highly likely” the miles will be credited by KLM and not the partner under these circumstances. Should this be either a yes we can credit to the partner or no we can’t situation? Why is there an element of luck or likelihood?