The piano with a thousand strings

I'm tuning a grand piano in a hall that keeps changing size — one moment a living room, the next an airport. The piano has far too many strings, hundreds of them, like it swallowed a harp. Every note I strike comes back slightly out of tune, as if the room itself is what needs adjusting, not the instrument. I keep telling the customer it'll just take a few more hours, and they keep nodding like they have nowhere to be.