Dear Ajarn, Although you are drawing a line under this, I have just a quick comment to make should you wish to publish it. The Thai labor law is black and white so although this is Thailand it doesn't depend on which way the wind is blowing etc.
It is clear cut and not open to any interpretation. Any first step should be to send a solicitor's letter to the employer requesting the expected severance pay. If you have a fixed term contract and the contract reaches its natural end and is not renewed then you have no case. Any termination can be made prior to a contract ending and this can be easily done by an employer however: If terminating there are a few, clearly defined things listed in Section 119 and these have to be properly logged by letter from the employer to the employee.
Termination can be made but severance pay must be paid as stated in section 67. Anyone employed in Thailand whether Thai, Western, ET, yellow people with pink spots must receive a notice period not less than their normal pay cycle - so weekly paid, your employer must give you at least a week's notice and the notice period must include a full pay period in salary. Monthly paid then must include at least a full pay cycle.
There is no gray area here. Always go with a Thai. Always speak to a supervisor if anyone tries to fob you off with the 'this doesn't apply to you' crap. Nearly all schools will settle at the initial arbitration meeting. In my case, from filing to having a face to face across a table with a mediator took just four weeks.
They will want to settle, as unlike the UK and possibly other countries, here in Thailand you are not able to seek the payment of legal costs from the losing side, so if the school doesn't settle they will need a lawyer ( very expensive and the cost is their cost alone )
The service is free maybe 80 baht photocopy costs for your filed documents and getting a Thai friend to translate everything English into Thai.