I disagree. She said yes, but only after increasing my deposit to an enormous amount. This was not disclosed to me when I visited the apartment or when I signed the form.

I disagreed with the terms of the contract, hence did not sign. If the terms of the contract are unknown to me prior to the application, how can I agree to agree to the terms prior to seeing the contract?

Again, CHF 150 is a small amount in the large scheme of things. But I don't think it's fair (even if it is common practice).