Charlatans

There is an agent outside Vientiane embassy that can organize a time for you if nothing online for 2000B. Not the best option but might help.

There a few companies online that allow you to get a flight with a 48 hour confirmation window for $12 or 15/

As Tod mentioned Ranong Pier crossing is open and seems easy BUT not an option if you have already done 2 overland trips already. You might be told from agents that it's possible but several people were turned back. If doing a border bounce I would recommend over Satun as the travel time is shorter.