They did do that for me once (bring a selection of things down for me) at the staff's suggestion in Monsoon in Cambridge, where of course, all the baby clothes are on the second floor with no lift.
The staff were lovely about it, but it's bloody stupid. And I wonder if they do it on purpose in a "these are not EVERYDAY baby clothes, these are special gifts from relatives to be worn sparingly baby clothes." way to make the prices seem less ridiculous.
And yet I still raid their kids sales...