The first type of delay is a human one; if you dropped off items, they may not yet be scanned as returns.
The technology delay is because My Account pages have a 5-minute caching cycle to load the pages faster. If you are not seeing results you expect, you can manually reload that cache (as opposed to clearing the browser cache):
Taking into account these human and technological delays, if you think your returns, holds or checkouts have not gone through, please contact us.