KCL sometimes likes to play a game called "let's wait till the last possible minute to give out offers and let's let UCAS autoreject some people because we didn't reply to their application in time". You're not alone. They played that game with me too last year. I'm sorry they've put you in this position, it's really unfair.
Even if you get an offer I would urge you to really really really think long and hard about going there, to a university that is doing such a disrespectful thing to you at the moment. I understand that this sort of behaviour from KCL extends beyond the admissions department and you might wish to avoid dealing with it for three or more years of your life.