I had the same problem! I was ok because after the money I took out, I still had over 3 months before my visa extension was due! They advised, if it was less than 3 months, I would have to start over again for the whole procedure of applying for a retirement visa!
My turnover was 1 day, and that gave me time to buy a ticket out of Thailand! I decided to get a return ticket to HCMC as that was the cheapest and was able to cash it in before I left Vietnam.