Your thai company must have thai who own 51% shares
You can't own but your company will own.
But nowdays government will remove and punish companies that use thai people as nominee in company.
Thai government seems to think about money but when it comes to benefit of thai. They care of benefit of thai more than money you invest. That's why big countries like china can never invade thailand as how they did to other countries.
this you may have to talk with financial department in government hospital. If there's any solution for this. But mostly they are not harsh like private hospital. Especially when you are Thai.
or you may request breakdown invoice (ใบสรุปค่าใช้จ่าย) from hospital directly. There will be lists of medical supplies and services that hospital have given for patient. You can assess if the cost of medical treatment make sense by breakdown invoice.