Why an old booking did not change when you updated the rate card

When a booking is taken, the prices in force at that moment are written onto the booking. Changing the rate card afterwards does not change it.

Why it works this way

A quote you gave a customer last week would otherwise silently become a different number on their invoice. The rate a rental was taken at is part of the agreement, so it travels with the rental rather than being looked up again later.

What a rate card change does affect

Everything booked after you change it. The new price applies from the moment it is saved, to the next booking taken — never backwards.

Checking what a rental is actually priced at

Open Bookings and choose Price this rental on the row. That prices it against the rate it was booked at, which is the figure that belongs on the invoice.