Yeah, I know how frustrating it is missing a flight. I missed one to Madrid once. I was only going for the day, to a meeting so had no luggage. When I arrived at check in there was a queue of trolleys a mile long. I joined they queue but after 10 mins it had hardly moved. I left the queue and went to the electronic check in but it said my ticket couldn't be used there. So I went to the fast bag drop but there were two guys with 3 suitcases each in front of me. I asked the clerk if I could jump the queue as I only had a few minutes left to catch my flight. She refused so I had to wait. When she eventually served me she said that the "flight had closed"!!!!!!
They got me on a later flight but I had to come back to Gatwick rather than Heathrow and then get a bus back to Heathrow to get my car. Very Frustrating