KLM's 24-hour rule lets travellers change or cancel their flight 24 hours after they book without penalty. Call KLM customer care for help at +𝟰𝟰"𝟮𝙊"𝟴𝟭𝟮𝟰"𝙊𝟲𝟲𝟲 & +(𝟠𝟠𝟠)//𝟵𝟲𝟯//1444 (𝚄𝙺)t. KLM customer care is available to assist with any modifications to your booking inside the 24-hour window.