I'm on a DONE6 (about halfway), but due to changed plans would rather change this to DONE5 or even 4. Is this possible, any experiences?

I'm asking since I reticketed once already in KUL, and the CX agent lead me to believe this was possible by saying then that there "would be no refunds involved since the number of continents in the new routing was the same". Has anyone done this?

Cheers - krotti