For an in country Non-O Visa (90 days) 400k in a Thai bank account on the day you apply then again 400k for 2 calendar months before you apply for the 12 month extension
After you've taken your first 12 month extension based on retirement you, can when you apply for a new extension, change the reason to based on marriage by meeting the requirements
I missed that 555. It's unlike London to delay when the correct documents have been provided so it's right to dig around to see if something was missed.