Do you still write Dear Sir/Madam if you don't know and can't find a name? I've seen a couple of examples of Dear Hiring Manager but I'm so out of touch I don't know if this is normal now, or informal or because a lot of examples are US based. I've trawled the website - no personal info is available on anyone apart from the boss and I've looked on LinkedIn but I can't find anyone listed under HR for their company. The phone number the website gives for general enquiries isn't recognised (tried on my mobile) so I can't call and ask, no email is given.