Dear Ad Agency,

Of course I can present work to your clients on your behalf. But really, giving me at least 24-hours notice would have been nice--for both you and me. On my side, structuring my work for a presentation instead of for implementation would have been helpful. On your side, more prep time means a more polished presentation and likely a better outcome. But, OK. I'll get up and present these concepts to the CMO of your Fortune 500 client three hours from now. No problem.

Love,
Me

P.S. The short notice will be reflected when you're invoiced.