I just got off the phone with a fantastic CM - first my tickets weren't showing up on
MDE since I changed to the new package, so they ended up just making a new reservation and will transfer the money I've already paid over to the new one. Now everything shows up, and I was able to recustomize my MagicBand to purple rather than Star Wars silliness (sorry, not a fan). She put my requests on no problem whatsoever - with the "this is only a request" caveat I knew comes with it.
I've never had a problem with a CM taking my requests. Our of curiosity, since you said "ringing" are you in the UK? I wonder if they have some different parameters for guests in other countries like some cruise lines do.