your wife is under your sponsorship so the company that your wife has been working with cannot do anything if she decides to quit. As husband sponsored, she should have a Work Permit ID issued from the Ministry of Labor. If she does not have the ID, then the legality of her working condition is questionable. The company is also liable for this.

I am also working under the sponsorship of my husband. I was the one who processed my working permit papers under the guidance of the company I am working with. Now, I have my Work Permit ID so anytime somebody comes from the Ministry of Labor, I have my ID to show to them.