Again,it's not actually illegal. It's the same when using an agent when applying for an extension at immigration. You're paying for it and the agent is paying immigration,but it's not officially illegal. This is a common misunderstanding among foreigners.
Immigration has the right to ask for the source of the 65k per month deposits based on retirement.Officially transfers from a personal bank account back home is not accepted even if it works in most provinces. Immigration might ask for a stamped and signed document from a pension provider showing you're officially retired.
A yellow house book is totally useless except for some provinces in isaan or northern Thailand.In "normal" provinces they might ask for a residence certificate from immigration showing the official address in Thailand.
You need to go for a 12 months bank letter from your bank,but most banks only issues a 6 months letter. They have to order a 12 months letter from the head office. My Bangkok Bank branch issues a 12 months letter,but that doesn't mean every branch does.