The most certain way is to create a small web page, include some SSI, name it with an SHTML extention and upload it.
<html><head><title>SSI test page</title>
</head>
<body>
<h1>SSI test page</h1>
<hr/>
<!--#echo var="SERVER_NAME" --> <br/>
<!--#echo var="Document_URI" --> <br/>
<!--#echo var="LAST_MODIFIED" --> <br/>
<hr/>
</body></html>
But if they haven't gotten back to you in 3 weeks, it might be time to look for a new host. The host I use usually responds within 24hrs.
-Theo-
(so many nodes and so little time ... )