in the webassist/email/waue_contact_2.php file, changed:
$MailFrom = "Enquirey@ Stag'n'Hen Do T shirts";
$MailFrom = "firstname.lastname@example.org";
most likely, you had it set that way originally, then edited the UE instance but did not upload the changed files
the code on the page isn't an error, it is a troubleshooting tool.
you can get rid of it by deleting this code:
<?php @session_start(); var_dump($_SESSION); ?>