In my job I deal with customs from both China and Taiwan everyday ... and with the new security measures in place, that is just the way it is in the times we now live in.
It is very difficult to get the big companies to understand that sometimes their product can sit in customs for up to four weeks, when their production lines are waiting for parts that go into their builds.
It must be even harder for the simple 'joe' to understand why one little 'something' he has ordered is taking so long ...
... but there is not much anyone can do to force customs to clear their shipments until they are ready to do so ...