Hi Tobs,
I called my local VFS this morning. I explained to them that I received the passport request letter from NDVO even though I live in a different region. They told me that the letter is global and therefore you can submit your passport and other documents at any VFS and they will send it to the respective VO regardless of where the letter is coming from.
In other words, based on what this representative told me, changing your VO is not necessary. I had already requested the VO change anyway but it seems we don't need to wait for them to respond in order to submit our documents.