I have a Non-immigrant category O-A multi-entry visa issued on 23 Aug 2017 and enter before 22 Aug 2018. I first entered Thailand 21 Nov 2017 with pp stamp admitted until 20 Nov 2018. In Sep 2018, I flew to Hanoi and returned to BKK 4 days later where Thai Immigration told me my visa had expired. They stamped my pp and gave me 30 days (until 10 Oct 2018) which is well before my prior until 20 Nov 2018 stamp. Is this correct? Do I have any options to restore my prior until 20 Nov 2018 date? Thanks for any advice.