You should leave your nameservers pointing at the Namecheap DNS servers. It's not the nameservers that need to change to use your domain with an e-voice site, it's just the DNS settings.
In a nutshell, the nameservers setting points your domain name at DNS servers. Then you use the DNS configuration to control what IP addresses your domain (and subdomains) point to.
e-voice does not provide DNS servers, so you should use the ones provided by Namecheap (or another third party service if need be).
So somewhere in the Namecheap control panel hopefully there is some DNS Configuration you can change. What you need to do is to set up an A record for www.buckfastleighguides.org.uk (and optionally buckfastleighguides.org.uk - i.e., without the www subdomain) to point to the IP address 22.214.171.124.
I see you've already added the domain to your site's control panel. So once you've set the DNS (and waited a while) then Bob should be your uncle!
Joe - Voice Admin
At this stage it seems that Bob is only a distant cousin, I'm afraid!
Thank you for the help; the settings I needed to find on the namecheap site were name something seemingly irrelevant, but I found them in the end!
I manage two websites with you, buckfastleighguides.org.uk and kingskerswellguides.org.uk I've completed all the steps for both and both domain names lead to the correct place when typed straight into the address bar. The only thing is, however, that while the e-voice 'site domain' settings for kingskerswellguides register the status as 'OK', for buckfastleighguides it alternates between 'wrong IP address' and 'OK, using remote IP'. Since the address itself leads where it should, I wasn't sure if this was a problem or not.
Thanks again =]
I think the settings are all correct - it's probably just a delay in the DNS changes getting round the whole Internet. It can sometimes take quite a long time for the changes to propagate everywhere.
So I expect Bob really will be your uncle in a few hours... :-)
Joe - Voice Admin