If the order was that mom was not to schedule anything on your time, then you should be able to enforce your visitation. You could call police for peaceful exchange if she is denying your visitation time. You could also file a contempt motion against her but that will take time. I think you can ask the police to assist you to enforce the order.
I am in full agreement with counsel above. I would call the police for a peaceful exchange and file a contempt motion is this behavior continues. In the meantime, I am located in Ventura if you wish to speak to be further regarding this matter. My office is (805) 650-1100. Good Luck!