I'm assuming that you settled your case by compromise and release (C&R), meaning that they agreed to pay you a lump sum of money, and you gave up your right to medical treatment? The C&R should spell out exactly what they are deducting from the gross amount of the settlement. If they claimed that they overpaid you temporary disability, that should have been specifically set forth. If there is nothing in the C&R about a deduction for a temporary disability overpayment, they probably are not legally able to take credit for it now. If you have an attorney, contact your lawyer right away. You may be entitled to penalties, interest and attorney's fees. If you did not have an attorney, go talk to an Information & Assistance officer at the Workers' Compensation Appeals Board. They will be able to assist you in straightening this out.
It is unclear why you received reduced temporary disability monies. If you were working part time then you would have been entitled to wage loss. You are entitled to 2/3 of your average weekly wage while temporarily disabled up to a maximum of 104 weeks. You do not give back any temporary disability monies unless there was a significant overpayment of TTD. The judge might give the carrier credit for an overpayment of TTD. The carrier is entitled to a credit for permanent disability in the overall settlement.
Sign up to receive a 3-part series of useful information and advice about personal injury law.