Cancel or change a miles flight with VS or BA

Has anyone had any experience of cancelling/changing a BA or VS flight booked using BA / Flying Club miles?
According to the web sites you get a full refund of all the miles and all the taxes etc. if you cancel for only a very small fee (£15/£25). Is that correct? Seems very generous.
I want to book a miles flight but my preferred dates aren't available so am thinking of booking the "next best" which probably means either the day before or LAX rather than LAS. And then if the preferred dates/destinations come available then changing either by canceling with one airline and going with the other or just changing within the airline.
Would be interested to hear people's experience - is it a painless operation?
According to the web sites you get a full refund of all the miles and all the taxes etc. if you cancel for only a very small fee (£15/£25). Is that correct? Seems very generous.
I want to book a miles flight but my preferred dates aren't available so am thinking of booking the "next best" which probably means either the day before or LAX rather than LAS. And then if the preferred dates/destinations come available then changing either by canceling with one airline and going with the other or just changing within the airline.
Would be interested to hear people's experience - is it a painless operation?