Thanks for your response.
I have purchased a signed cert from RapidSSL. I followed the instructions from the ISPConfig help. We pasted the cert text into the SSL Certificate text box, selected save certificate from the drop down box and then clicked save. When we navigate to the website, it still shows the self-signed cert. We have restarted the apache and the server to see if this would work, but to no avail.
Any help will be much appreciated...