TG992 is right. They pulled out of Bangkok in 1998 when the Asian Crisis hit.
There was a rumour going around that they were going to start back flying there. But it now looks like they are going to Code-share.
There is also a rumour going around that they are going back to Seoul-Incheon.
To be honest Kiwi dave I don't think TG will return to CHC at least not in the near future as TG fly daily to AKL. If Air NZ and Thai start codesharing I think you will probably be able to connect to NZ at AKL with a codeshare with TG domestically.