Child Support/Spousal Support enforcement in California

I live in California and have 2 children. We negotiated our divorce through attorneys and agreed on the following: Child support in the amount of $500 (total) until some property was sold, then the support would raise to $750. Spousal support of $100 per month for half the length of the marriage based upon him keeping me employed in the company we owned together (but I gave my interest back to him, based upon the agreement). The employment was to be at my same salary level, car payments made by the company, gas, car insurance and health insurance all paid for by the company (a corporation). He has only made about 2 child support and alimony payments in about 9 months. I agreed to ridicoulsly low amounts for both spousal and child support just to get an agreement. I only received salary for my employment for about 2 months and worked the other months without pay in the hope that the business would do better financially and I would eventually get paid. My question is, how to I get the child support order enforced and what if he is showing no income but making a $5000+ house payment and paying for 2 cars out of his company. In my divorce agreement, it was written in that the alimony could be revised if the one year employment agreement was not kept. Also we share custody, by I am primary. He visits only when it's convenient for him and is unreliable. The divorce agreement states I could only move 25 miles from where I live now. I'm having a hard time finding work to support myself and the kids without him helping. Do I have a legitimate reason for moving beyond the 25 miles to find work. Incidentally I've had to call the police on him 5 times over the last 10 months for harassing me. Any advice would be appreciated.

[tbyte]

First, I would not say that you agreed to ridiculously low amounts for spousal support and child support. Rarely, if ever, does either party feel that they got a great deal out of their divorce, and in your case the amounts seem to be about typical. Regardless, you agreed upon them and that is that.
But....
...your ex IS legally responsible for holding up his end of the agreement, and you should enforce this rigorously. Take him to court for contempt, and let him know that you will be asking for attorney's fees and court costs from him.
Also, I assume that you have a set parenting schedule. Let him know that you will follow this schedule strictly, and if he does not arrive to pick up the children for his time with them, you will not allow him extra time later. You cannot make him have contact with his children, but you should under no circumstances allow him to interfere with your schedule.