I will reinforce the point of just finding any agent instead of going out your way for a concierge.

Best case scenario, they rebook you the same way any agent would've been able to.

Worse case scenario, they tell you to wait a few minutes while they fetch an agent that actually knows how to complete a rebooking.

So unless you're specifically looking for someone wearing a black jacket give you a boarding pass, you will be infinitely more productive just finding any agent and letting them know which other flights/routings you've thought about that could help you get rebooked.