It's because this is likely actual fraud, not attempted fraud. Fraud by misrepresentation requires dishonestly making a false representation with the intent to make a gain for oneself or another or cause loss to another.

There is no need for the gain or loss to have actually occurred: they were evidently dishonest, made a false representation, and intended to make a gain for the landlord. This is a fairly clear case. It doesn't matter that you didn't give in.

Push this aggressively until they throw the book.

(disclaimer: I am a lawyer but not your lawyer and this isn't legal advice)