i used the post office counter in Press and Books today. The lady was friendly.
As one who eschews postage labels in favour of proper stamps it was quite an effort to get the stamps I needed (for a single package!) however as they had low denominations such as 10c and 50c as well as some higher ones, I was able to make up the desired amount I had to do the maths and explain exactly what I wanted though, rather than relying on the counter assistant to do it.