The argument that you were offered "new" work is valid. The thing is that a refusal of work has many more loopholes to obtain benefits. To further improve your chances of getting UI, say that you were "fired/discharged" when you applied because it's true. Your contract ended. Then on your first claim form, you check the "did you refuse any work" box. That way you are in no way committing fraud.
CBG is so right about not working under the new terms. In your case, you had a chance to think about it, you'll have to sign a new agreement, and once you do that, you can't go to UI and say, "I changed my mind. This commission only structure was too much of a cut in pay." The UI system doesn't protect you when you've negotiated the agreement, but it might be there when the employer tries to make you take something you don't want.

