In my experience that's usually futile. There's a good chance the previous owner, if still alive, didn't have service or even know what it is.
Having been in a similar position, rural telecommuting, I assert that the guy's both being jerked around with and being a twat. Both cablecos and telcos don't give a shit about sparse customer density areas. Where I lived a few years ago, VZN refused to drop a DSLAMM in the local box. Comcast was a mile away and wouldn't even return calls re extending.
What one can do:
o Buy another place instead that has demonstrated connectivity available. Trusting the providers or the ludicrous gov site was just plain stupid.
o Get ISDN and live with the speed.
o XO is hardly the only leased line provider, is Broadwing still around, or Speakeasy? $500/mo would hardly be onerous. Either he could write some of it off, or makes enough $ for that to not be a burden.