well at the time the visa free entry was only 30 days and then you got a 30-day extension. So the agent saw that I had done the extension while I was in Thailand and told me I already did an extension he didn't want to let me back through into Thailand. My brother was with me who had done the same thing but had no problem. Luckily the other agents talked my agent out of being a huge inconvenience 😂
I did the poipet border crossing as my first ever border bounce. The train was about 5 hours, then walk about an hour. Stayed for 2 weeks in Cambodia and still had issues coming back across that crossing. They let me through but i havent used it since. To better understand, it is not thai immigration that is the issue it it Cambodian immagratiom agents that deny you. Also if you are going alone as a female I would not reccomend this trip. Everywhere in Thailand is fine but you dont want to be alone stuck without a plan in poipet.
If you dont have one already go create a western union account. You can transfer from there and see all the options and prices. I.e. debit card to bank, bank to bank, bank to cash pick up ect..
For example i just transfered money on friday when the online rate was 33.99 per USD (you will always get less than the online rate) and they gave me 33.48 per USD and charged me $0.99 cents usd.