I just posted this on another thread a few minutes ago.
Last week, I when updated my into, I incorrectly typed a wrong # on my exp date. Once I corrected it, I again had to wait 10 days for the info to be updated.
So even though you are just changing your exp date - it is like adding a whole new card with a 10 day wait.
Anyway, way Etsy DC could correct this - and have an update link that would not be considered as entering a new card as long as the Acct # is not changed??????