I was told a couple of years ago that it's only possible to change visa at Immigration 1 in Bangkok, if it's still true or not that is another question!

And if it's still true then going to Savanaket a better option. I tried once to change visa from tourist to Non-B at immigration 1, it took long time and the officer was rude and unprofessional, I had to go back to Kampeng Phet 3 Times to get new documents... My friend had done it the week before with no problems so I used his application as a blueprint for what I would need and still it was not OK.

I was told a couple of years ago that it's only possible to change visa at Immigration 1 in Bangkok, if it's still true or not that is another question!

And if it's still true then going to Savanaket a better option. I tried once to change visa from tourist to Non-B at immigration 1, it took long time and the officer was rude and unprofessional, I had to go back to Kampeng Phet 3 Times to get new documents... My friend had done it the week before with no problems so I used his application as a blueprint for what I would need and still it was not OK.

You are talking about visa conversion, within visa validity.

OP issue is a change in extension of stay, at expiration.

Completely different things.

Aha ok, thanks for correcting me!