My wife works for a company that created a new base-plus-commission customer service position. She is the first person to hold the job. Her commission plan is very vague and broad. She has been paid on numerous (small) jobs. Now she has worked on a BIG job, and the company wants to change the rules of her commission AFTER THE JOB IS FINISHED so it doesn't have to pay her anything.
What is her recourse? Her HR isn't very supportive (it is the company's representative, after all). Is there a governmental agency she can contact, such as state or federal Wage and Hour? Or is she going to have to sue them?
Thanks for your help.

She can sue in court if they will not pay as agreed in a pay contract.

While a company can change the pay system anytime they want, they can't change it on pay already earned.

Does it help or hurt her that her commission agreement is vague, and that the company has paid on projects that are exactly the same, only smaller?