The problem being that I cannot create nor retrieve said billing setups even though I'm authenticated with my top-level manager account.
I earlier posted about this same issue and was told I'd need to talk to a representative or my account manager. Being that I am in fact the manager of the account I'm trying to contact someone that may be able to assist me.
In essence, I'm trying to run ads on managed accounts created through the API but cant because it won't allow me to set up a billing setup