Unfortunately I do all the ticket booking myself and not through a TA.

It made my blood boil when the call centre staff told me that the reason the seats are blocked is because they are blocked. Sounds bloody condescending.

I have very strong doubts that SQ will read the note as I was also wondering if I had the a remark for the flight, won't there be other remarks from other passengers?

Who will take precedence? A pax with higher elite status booked into lower fare bucket or a pax with no elite status but booked into the most flexible fare?