Please be advised that there is an immigration office in Surin Town as well as in Kap Choeng.
So for those of you who live in Surin town or near by it means you don't have to go to Kap Choeng. When the Thailand - Cambodia border reopens Kap Choeng immigration office will be swamped once again as it was before the pandemic shit. I have been doing my last two extensions (retirement) in Surin Town and the whole process took about 30 minutes