Background:
Most of my travel is on 'W' fares, which is what usually comes up on united.com when you book your ticket with the 'lowest refundable' option.

I made a mistake on one of my internet bookings and called the 1K desk to make a change. The agent indicated that they would have to charge me $100 in order to fix my mistake, as 'W' fares were not refundable. I politely explained that they were refundable according to united.com, and she spent a little more time checking, and came back confimrming that I was correct, and this was a refundable fare. Furthermore, this very polite and apologetic agent said 'Thank you very much for teaching me something, as I never look for W fares when a customer asks for a refundable fare.'

Just thought I'd pass this along as it may help someone else who's looking for low refundable fares.

Also, I checked Oz's booking code thread, and 'W' fares are not listed as being refundable ... is this a recent change to these fares?