One of my clients owns all derivatives of theirname.xyz (i.e. .net, .co.uk, .uk.com) apart from .com
The .com is not currently in use, in fact it is owned by someone who says "Buy this domain for £x thousand".
Under .com best practices there are ethical guidelines which shouldn't include holding on to a domain you are not using for profiteering, however I have contacted the domain registrar who doesn't get back to me.
Are there any appeal panels I can go to - i.e. the US equivalent of Nominet.