It sounds as if you should start reading some documentation.I tried what you said by entering the dns servers in the /etc/network/interfaces and restarted networking. I was unable to ping anything. It still uses resolv.conf. Before I restarted the interfaces, I put a # in front of the entries in the resolv.conf.
I read some where you can uninstall resolvconf, but that failed as well. It says the is no package to uninstall.
I though by restarting, I might get different results, but that made it worse. I was locked out as it uses Kerberos and if it can see the kerberos sever via dns it can autheicate. Luckliy it was a VM so i could break into it.
I tried similar test on a clean install of 12.04 and yes the settings in resolv.conf get overwritten. So can I presume where the servers have been upgarded from 10.04 to 12.04, they arent effected by this new overwriting "feature" of 12.04?