You could file a motion and ask a judge to address it or to refer you to mediation to address and, pending mediation, to order an interim solution.
You could also pick up the kids and let her know via text that they'll be available for her to pick up at X ' Clock as per the arrangement, that they'll be ready for her to pick up, but that you won't be driving them back? It'd a little aggressive, but it might prompt a conversation, and she can't claim you interfered with the order if it says to share transportation and she's refusing to do s.
IF YOU LIKE THIS ANSWER AND APPRECIATE THE TIME IT TOOK TO WRITE IT, PLEASE SELECT IT AS "BEST ANSWER." Thanks. The above is said without seeing your case file and without my understanding the entirety of the facts of your case. Depending on those facts, the above information be may incomplete or may be completely inaccurate. The above is intended as general information only based on what you described and not as legal advice. I advise you to consult with counsel who may be able to provide better information commensurate with a better understanding of your situation.
The most common tool available to litigants seeking to enforce a Court Order is a Motion to Enforce Litigant's Rights, set forth in Rule 1:10-3, “relief to litigant.”
1:10-3. Relief to Litigant
Notwithstanding that an act or omission may also constitute a contempt of court, a litigant in any action may seek relief by application in the action. A judge shall not be disqualified because he or she signed the order sought to be enforced. If an order entered on such an application provides for commitment, it shall specify the terms of release provided, however, that no order for commitment shall be entered to enforce a judgment or order exclusively for the payment of money, except for orders and judgments based on a claim for equitable relief including orders and judgments of the Family Part and except if a judgment creditor demonstrates to the court that the judgment debtor has assets that have been secreted or otherwise placed beyond the reach of execution. The court in its discretion may make an allowance for counsel fees to be paid by any party to the action to a party accorded relief under this rule. In family actions, the court may also grant additional remedies as provided by R. 5:3-7. An application by a litigant may be tried with a proceeding under R. 1:10-2(a) only with the consent of all parties and subject to the provisions of R. 1:10-2(c).
You should document the communications that you sent to your ex-wife wherein you directed her to the applicable provision of your agreement and requested that she comply. Once you have done that, you can file a Notice of Motion to Enforce Litigant's Rights. If you use an attorney, they can request counsel fees from your ex-wife on your behalf. If your agreement is clearly worded in your favor, you may be able to argue this motion on your own, pro se (without being represented by counsel). Unless you're an attorney, you won't be able to collect counsel fees for such a motion. Also, your case may be more complicated than you have suggested, justifying the need to hire counsel. I typically recommend consulting with a lawyer before one chooses to represent oneself in Court.
Mr. Murray's response is NOT legal advice and does NOT create an attorney-client relationship. You should NOT rely on this response. Mr. Murray's response was generated without conducting a full inquiry as would occur during a face to face attorney-client consultation. It is likely that the response above may be made less accurate, or become entirely inaccurate, as you, i.e. the questioner, disclose additional facts that should only be discussed during a private consultation with an attorney. I strongly recommend that you consult an attorney who is licensed to practice law in your state, whereupon all relevant facts will be discussed. All responses posted by Mr. Murray on Avvo.com are intended as general information for the education of the public, and not for any specific individual.