Whenever virgin media have email authentication problems (happens several times a year, as it's gmail under the hood), the only way to get email back on SWMBO's ipad is to delete and recreate the email profile / account. Nothing else works - it should (most overworked word in IT, that) not be necessary, but is.
Is this a local thick email client (Outlook / Windows Live mail / Thunderbird etc.) or a purely webmail connection? If the former there's lots of settings to get just so, if the latter it's a bit weird.
SD