Sorry to have deleted that thread.
The guy's wife went to the Nong Khai Border, stamped out of thailand, took the bus across bought a visa and stamped into Lao, turned right around and rode the bus back to thailand.
She failed to stamp out of Lao and also failed to stamp back into thailand. This happened some months ago.
The only way to resolve it is to go back to the Nong Khai border.
Face it failure to get stamped in or out of the country happens EVERY day and she's not the first foreigner to do this.
I don't even think she'd be charged overstay in thailand because in theory she's not here. She could be charged with illegal entry but that's very, very unlikely.
I think it's far more likely the thai officials would send her across the bridge to the Lao side to sort out the overstay on that side AND to get a stamp out of the country, then she can come back and stamp back into thailand.
TLDR : Answer Summary
A foreigner who failed to get stamped out of Laos and back into Thailand should return to the Nong Khai border to resolve the issue. It is common for such errors to occur, and while the individual is technically not overstaying in Thailand, there may be concerns about illegal entry. Thai officials will likely guide her to rectify her entry and exit stamps, and any penalties may be managed on the Lao side, where overstay fees apply.
