How can you tell the difference between 'Let's say that we have not done it' and 'We say that we have not done it'?
No difference really :) both work!
Everything in this section sounds like something either a mother, a girlfriend, or a collection of children would say. This falls in the later.
"We haven't done it! Nobody saw us doing it! You cannot prove anything!" In my mind's eye, I see Bart Simpson say that.
Have not done it!!
"we say that we have not made it" was what I wrote and it was marked as correct.