My Doctor at Bumrungrad said it isn't available in Thailand. He suggested to look around in neighbouring countries such as Hong Kong, Singapore or Japan... Would anyone have useful info?

For sure available in Japan, Singapore and probably Hong Kong.

 

Least expensive of these (but still very pricey) would be Singapore. Suggest this doctor at National university Hospital  http://www.ncis.com.sg/patient-and-visitors/find-a-doctor/associate-professor-jimmy-so.html

 

It is also, of course, available in the West. If you are eligible for free care back in farang-land this would be a good  time to go avail of it.