I'm pretty new to this whole Skyteam seat selection fun, have searched but can only find DL-KLM/AF seat selection problems.

I have a ticket issued on China Southern 784 stock but with most segments operated by KL, all KL flights are marketed by CZ and has CZ code share flight number.

Called CZ for seat selection, they said oh it's operated by KL so you'd be better off calling KL coz we can't do it. Called KL, they said you know what it's issued by CZ so call them, we can't touch your ticket if it aint got issued by us...

I'm pretty new to Skyteam, but being used to somewhat slightly better functioning cross-carrier IT platforms at Star and Oneworld, this is just shocking. Am i really, like what CZ and KL told me, left with no options but selecting seats at T-30h when online check-in opens?

Thanks folks.