I don't think that you understand. If the Trustee says that your Chapter 13 Plan requires the payment of your tax refund, you do not get the option of ignoring your plan or the Trustee. Failure to follow the plan or the Trustee's request will result in the eventual dismissal of of your plan. The judge may add a restriction on refiling ANY bankruptcy at all for up to 2 years. Defying the Trustee is never a good idea.
The only thing that you can do is tell your attorney to file a motion asking for permission to use the tax refund or skip a few payments, so that you can finance a necessary move. If your attorney is reluctant to file such a motion, it may be that they have good reason. Be sure to ask and take notes on what they say. Then you can consider calling the trustee and asking someone in the Trustee's office to discuss filing such a motion with you. You may consider getting a second opinion about whether such a motion is possible or advisable. Good luck.
This answer is not intended to create an attorney-client relationship and may not be relied upon as legal advice. A careful examination of the facts is necessary before a legal answer may be relied on. You should consult your own attorney before taking or refraining from any legal action.
You won't go to jail for failing to turn over your tax refund to the trustee, but your Chapter 13 can & probably will be able to have your Chapter 13 dismissed for failing to comply with the terms of the Plan. Try to work this out by repaying the money to the Trustee as soon as you can, unless your Chapter 13 is no longer important to you. Whether you will lose your car or not will depend on the terms of your plan. Hope this perspective helps!