So is it switching or extension?
It's both
<small rant> It seems that whichever term would be to your advantage, the opposite term applies. If it'd make it more likely that your application would be approved if you're "switching," then you're not, you're "extending." If it would be cheaper if you're "extending," then you're not, you're "switching."
Whichever one I'm doing - "switching" or "extending" - I'm looking forward to the process being over. </small rant>
That's directed toward the process and the bureocracy, not toward you, Vicky.