Policy changes after you already received your passport won't affect it, only your future passports. Your document is valid until the date written on the document itself, so 12 April 2027.
You need to go to your immigration office and ask them for their handout for the extension. It will list everything you need specifically, that way you can gather it all and bring it for your extension.
Nothing new to affect normal people here. The only thing this article says is that banks must check people applying for an account against the blacklist of known scammers and mule account holders. If they weren't already doing that, they will do it now because they banks will be responsible to refund scams if they don't check
I've spoken to a Phuket immigration volunteer, and he said the success rate for DTV extension applications in that office is about 2%. In Chiang Mai they will not accept a foreign bank account statement even though the official rules say it is okay. Even the immigration officers are recommending people do a border bounce to get a new stamp rather than try to apply for extension. It's possible to get one, but it's not that easy.
Only chance is Pattaya unless he wants the agent to help apply for the non-O as well. In Bangkok, agents don't only offer bank accounts, they offer it as part of the package.