The KHRG in a documented report lays out the sort of dangers and human rights violations the refugees in Tha Song Yang District, Tak Province, would face if returned to the area around their former homes. (It was dated 27th Jan but I have only just seen it.) I YOU have not yet written to the Thai government (why not?) you might add a mention of this report. It concludes:
Returning refugees thus face serious risk of injury by landmines. Returned refugees would also face human rights abuses including conscription as forced labourers working on military projects, portering supplies and clearing landmines as well as reprisals against them as accused KNLA supporters. For these reasons, no refugees from the Ler Per Her area should be forced to repatriate against their will. Moreover, refugees should be included in any future negotiations regarding repatriation or relocation.