Need extra time to fill in pip form

I am really struggling to complete the Pip2 form and it has to be in for next week. I just cannot get it done and posted for then
I know I have to phone them to ask for extra time but I dont know what is best to say. The form arrived late anyway but when it came I couldnt start it because I had got so in a state about it and went into a deep depression so didnt do any of it at all for almost 2 weeks. None of it is filled in yet. How should I explain as I didnt let them know this 2nd form was late (the first never arrived) and I cant prove I've been too ill to start it. Do they normally give extra time in these circumstances?
They did have to give a later date on the 2nd form as the first didnt arrive so this would be a 2nd extension of time

LiB

There should be no problem with you getting a two week extension just given them a call and explain that you are struggling to return it by the original date, I would not expect this to be a problem.

Gordon