The fee is agreed with the agency before the date, never on the spot.
In most cases part of it has already been settled as a deposit. The balance is then handed discreetly to your hostess in the first moments of the date, in cash, without her having to ask. Where no deposit has been paid, the full agreed sum is handed over in the same way.
Should you prefer to have nothing to hand over on the night, the whole amount may be settled in advance through the agency, by card or by bank transfer. That is in any case the rule for a journey or a larger sum.
The amount is not open to discussion when your hostess arrives: it was set beforehand and she has no latitude to change it. She may discreetly check the sum handed to her, which is simply the custom.
