The way it's been stated is that Billing is the only one who can make the decision whether to move a WOW account from one Battle.Net to another. So none of the Blizzard reps here could tell you yes or no - it's not their area. It has been done for some people, but there is some policy they have to decide.
Technically, there isn't a "merge" of the Battle.Net accounts. Instead, the accounts on one Battle.Net would have to be moved to the other. Perhaps when you call, ask the question that way - as they'd say no to a merge (which can't be done), but might say yes to moving a specific WOW account from one Battle.Net to the other, given that they are all in your name.