EY is being responsible by repeatedly reaching out to you about the schedule change. You might be fine with the new timing but EY needs you to acknowledge that, because they'll need to reissue your ticket. It's fair enough to wait a while to consider your options because it's a one-time offer, but you have to do something sooner or later.

If you continue to ignore them, you might well run into issues down the road: segments dropping off the booking entirely, issues at check-in, or EY just accepting the new schedule on your behalf.

How far out is your trip? If you're travelling within a month I wouldn't leave it for much longer.