Just cancel it saying wrong address or the like. Then block them on your
site to prevent future headaches for yourself, because they're either an
impulse buyer or whom just don't pay enough attention to what's on your
listings.
It's not being resistant to change, it's the time/headaches of having to
adapt to new formats that basically do the same thing but just more
cumbersome. More mouse clicks, more new page opens, just more of many
minute tasks that add up over many list...
