What the figure buys
The clock starts at her knock, and every minute from then until the booked length ends is spent in her company: talk, dinner, a drink, a quiet hour. That is the whole purchase. Fees are for time and companionship only; there is nothing further to price, offer or sell, here or in the chat.
Folded into the same figure are her cab to any Zone 1 or Zone 2 address and the desk's share of the work, from the opening reply to the note that she is in the lift. There is no service charge, no premium for the small hours and no supplement for a suite.