I would tear her points apart one by one.
"As we discussed in our emails dated 5-15, 5-26 and 6-2, a cake to serve 40 cannot be made as a 4-tier cake, which is why it was agreed yours would be 2-tier. The original 4 tier cake in the photo serves about 175 people. Another of the differences you point out is your cake has no bows. In your 7-1-08 email, paragraph 2, you directed me to leave off the bows. Another difference you point out is no pearls. In your 7-4-08 email, paragraph 1, sentence 3, you directed me to not put on any pearls. We had a number of email exchanges where I informed you that fondant and BC do NOT look the same ... see our emails dated 6-25-08, 7-2-08 and 7-12-08."
LOLOLOLOL My words exactly! If people change it too much, I usually find a picture of a cake closer to what they're REALLY describing and say, "You mean like this??" LOL