Is flying into Vietnam from Phuket then back to Phuket a good border run? Thanks

Hi, can someone give me some advice please? I arrived in Thailand on 7th June, believing I had a 90 day visa - my travel agent had assured me that I had. It turned out I only had a 30 day visa, but by the time I realised (my fault, I should have checked) I was 27 days beyond my expiry date. I then flew to Kuala Lumpar and back. Since then I have had 2x 30 day visa extensions from Krabi Immigration either side of another return trip to Kuala Lumpar. My visa expires on 28th November. I would like to stay til end of January 2020, but I am aware I have already left the country twice for visa extensions. Is it feasible for me to get another visa (60 days), and if so how should I go about it, or should I head back to the UK and try and come out again at the end of January on a 60 day visa? Thanks