Continuing my own previous comment, my vague memory serves that I got my BP at JAL(??!!) counter with the help of the servant agent whom I met at arriving gate.
I might remember totally wrong thou, so dont take this too serious.

Anyway, I would simply suggest to search an agent on arrival and explain the need. Thats Singapore anyhow, they do service miracles there, what happened to me as well back then 😁