If banks cared about foreigner difficulties opening banks accounts it would have been dealt with long ago as there are many visa classes opened much longer than DTV and still can’t open banks accounts, if you think a ‘manager’ is going to update you about anything you simply don’t know Thailand at all 🙏🏼 what is known is that a DTV is a tourist visa and as such a agent will be required and even then it might not work as it has become much more difficult to open banks accounts accounts
Your family will be contacted to decide how to dispose of your remains, this could be via your family in Thailand or a will etc
If you’re alone in Thailand and no overseas family the body would likely be disposed of according to local government regulations and a holding period for collection of your body