cancellation 2 hours before the meet... whats your protocol

happened to us 3 times in the last 6 months and each one stings worse than the last. we get a sitter sorted, wife does the whole shower shave outfit ritual, im on my way home from work and BAM message at 6pm for a 8pm meet... "sorry somethings come up". how do you handle this? do you block them, do you give them another chance, do you ask for a proper reason? im starting to think we need a rule like 2 cancellations and youre out but the missus says thats too harsh cos kids get sick and stuff. genuinely curious how others manage this cos right now were just letting it ruin our weekend each time