Cepstral Community

I am new to text to speech usage and not yet up to speed on phonems, does anyone have a freecustom lexicon with correct ponunciation for NZ and Australian placenames. Some are OK, but some the voices I am using just canoot render correctly scuh as Dunedin NZ, which all of the four voices I'm using (AMY, LAWRENCE, MILLIE, WILLIAM) insist is "Dunnydun" not DUNedin, or GreyMOUTH, (my birthplace) which they insist is "Greymth", I hate to thing what they'd do to Murwillumbah or Yackadandah!