'not really up to date...'
Can agree with that. I've been through quite some pain to get my Social Security health benefits changed to the voluntary payments process after retirement (Section 39).
Had to be done through the local Social Security regional office here in Chiang Mai.
Local senior guy here is Chiang Mai (CM) asked for a copy of my visa showing the expiry date. I responded that I've had Thai Permanent Residence (PR) (for 27 years) which is for lifetime meaning it has no expiry date (but auto cancels on my death).
Response from CM senior 'Thailand does not have PR but anyway send a copy with the expiry date.
I called the Social Security hotline 1506 and eventually spoke to a polite pleasant lawyer in perfect English. She said she was not surprised at the comments from the CM senior office, because they receive no training or information whatever about any other aspects of Thai administration, policies, other ministries etc. She kindly called the CM senior guy and explained what PR is, it's for lifetime, no expiry date.
I quickly then got an e.mail from CM guy asking for a copy of my PR book (expiry date not mentioned in his e,mail).
Then fairly smooth sailing to get my membership changed to Voluntary Insurance / member pays every month.