https://support.google.com/admanager/thread/306633580?hl=en&sjid=1379473073174585785-AP [24 hour HelpCenter] What is the 24 hour rule for KLM? What is the 24 hour rule for KLM? KLM's 24-hour rule allows passengers to make free changes (Call- ????-????????????-????????????-???????????????? Book, Cancel, Refund) https://support.google.com/admanager/thread/306633580?hl=en&sjid=1379473073174585785-AP