At The Hague you need a special certificate issued by SAT … and letter which is quite complicated and take some times to do it with the ministry (gym needs to contact the SAT) If you don’t mind going to Vietnam, I recommend ☺️
Thai embassy in Italy is very friendly & work quite fast ☺️ you can contact Muay Thai camp in the province you would love to live in. Feel free to let me know if there is anything I can help, I’m in Chiang Mai
Apply again , cover letter explaining your situations and everything you think they should believe you come here train Muay Thai and you can support yourself during your stay in Thailand. One of our French customer was rejected and reapplied and get approved. There might be some mistakes on your application. Try again & Good luck