I just got a call last week about a colony in a brick chimney myself. I really don't want to deal with this but I told the tenant that I would come by and take a look since I'm not far away, then advise on what she might do. The landlord is claiming it is her problem, but neither she nor I think he has much to stand on with that argument. She estimates the bees have been there since at least last February and just now decided to try and do something about it. The colony is up near the top, beginning about 12" down and extending about 36", and almost all the way across the flue, leaving only about 4" open. All but the last two combs are connected all the way across to both sides, and this thing is holding LOTS of bees.
I've told her that a trap out is probably the best, if not only option and that now is not the time to do it. If she is willing to wait, I've offered to go back and protect the opening (no arrestor or cover of any kind) so they have a better chance to survive winter. If she agrees and they make it I'll probably help her recruit another keeper to trap them as I'm not too eager to give it a go myself, then suggest she bring in a sweep to deal with the mess. Maybe I'll change my mind by March and take it on as a learning experience, but we'll see. The alternative is bringing in an exterminator and a sweep, so I hope for the bee's sake her patience holds up.