Can always employ sly, underhand tactics! 
Tell them, "Oh dear... the hotel function room I booked can only
accommodate 20 tables! You folks need a total of... 50 tables, ah?
Last I checked, only the 6-star Conrad Hotel has a function room
that's big enough, and still available. But, the thing is, each
table will cost $980!! Do you still want to proceed with
that?"
