Then don't sign off on the extension, and make the agent go back to court and ask the judge to extend it. You'll have a better chance of successfully opposing that request if you hire post-conviction counsel. Good luck.
This answer is provided for general information only. No legal advice can be given without a consult as to the specifics of the case.
Attorney Witt is dead on and you should force the PO to meet his burden to change the original sentence. If you need assistance it sounds like you should consult with a Wisconsin licensed attorney that practices criminal law, whether a private attorney (which seems a good investment from your perspective) or a public defender (they one you had before, or may need to apply for). Good luck.
Please select "Helpful" and/or "Best Answer" if appropriate. Know this answer is for informational purposes only. Realize, by answering this question, no attorney/client relationship is created between the question poster and JCWB ESQ LLC <http://jcwbesq.com/>. Although the response is an effort to assist, with the facts presented, it may not be appropriate and/or the best solution for your entire situation. The best way to handle any legal problem is to seek the advice of an attorney licensed in the jurisdiction where the issue arises.