This weekend in particular?

This weekend in particular?

Our local BigC (Phuket) has a Western Union branch inside, and that's open 7 days a week

In Bangkok the small booth close to Asok station (go down the stairs to the black swan, turn right and it's a little way down, just before the hotel) has been open, for me, when everywhere else was not.

Good luck.

I don't know about any other places, but in our town, WU is run through Bank of Ayudhya - including its Exchange kiosks. That means you can get/send money whenever Exchange booths are open.

In Chiang Mai it was only open during the week.

This weekend in particular?

They are also located in Central Department stores. So my guess is if the store is open then they are too.

in post offices too, the one next to the mall Ramkhamhaeng is open til 9pm 7 days a week

I don't know about any other places, but in our town, WU is run through Bank of Ayudhya - including its Exchange kiosks. That means you can get/send money whenever Exchange booths are open.

This is true about the kiosk that I mentioned, although it's open much longer than banking hours.