Sorry this is happening to you - a hard lesson in this business of why many of us do not do special and also why most of us get paid in advance of care and take a security deposit

You could take her to small claims court if she is in violation of your contract - but it will likely cost you more in time off and lost income and still no guarantee she will pay even if ordered to - so than you'd have to go through trying to get her garnished and so forth