Nigel Farage said "I'd like to spend this money on schools, hospitals and GPs", the big bus slogan read "we send £350million a week to the EU - let's fund our NHS instead".
So nobody promised or made a pledge, and indeed it's ridiculous to try and hold them responsible - the Leave campaign were asked over and over again in a cynical, sarcastic fashion what we should do if we left the EU and these sorts of suggestions are what were made. Now they're being treated as promises even though people like Farage are in no position to enact them. You think we SHOULD spend that money on the NHS now we're leaving? Great, lobby your local MP.