Headz Up for people in Bangkok
It appears 90 days reporting by foreigners can no longer be done at either Imperial World Mall (Big C Lad Prao Soi 83) or at Big C Ratburana Road (across the river in Thonburi).
People who went there the past couple weeks have been told to go to Chaengwattana. I don't know the exact date they're not accepting them but I wouldn't waste a trip finding out :(
TLDR : Answer Summary
Foreigners in Bangkok can no longer complete their 90-day reporting at Imperial World Mall or Big C Ratburana Road. Recent visitors have been directed to Chaengwattana for this process, but reports indicate long wait times due to combined queues with visa applicants from neighboring countries. Some suggest that doing the reporting by mail may be the easiest option.