This is only for Bangkok Bank. If the money you want to use for immigration has not been in your account for 4 months when you want the letter, then you must sign a document allowing them to freeze the funds for 4 months from that date.
It's nothing about them not issuing the letter, they just require you to freeze the funds for 4 months to do so. Yes this is still the policy at Bangkok Bank and a strong reason for anyone using that bank to go elsewhere.
the fact that he talked about an immigration matter related to fast track means it was not regular fast track, which is just using a different line.
He is talking about safe entry, where an agent pays immigration to guarantee you'll be admitted into Thailand even though you've been abusing tourist entries trying to live there.
But you're not talking about fast track. You're talking about VIP fast track (safe entry) where an agent syncs up with immigration to guarantee your entry.