Smooth driving but strange "office hours"

Staff were helpful, though I was rather annoyed that the office closed at 1pm on Saturday. That was the time I'd inputted into EasyRentCars because it was either that or 2pm, and my timing was quite tight. it meant there was no warning - other than the very small print of Green Motion's "booking voucher" or when I phoned them to explain our situation. Anyway, they were very helpful but did charge an extra £36 to have someone available out of their normal office hours to facilitate pick-up. There should have been more warning. Did they deliberately lower the price for this particular hire time through the broker, knowing they could "sting" me later for the £36 charge, or take my £15.50 reservation fee if I'd elected to cancel? I don't know but it has been a troubling part of an otherwise positive experience.