How do I sue gieco, I was assigned an adjuster out of my state

You would not sue the individual adjuster.  You would sue Geico Insurance Company itself.  And then you can serve them at the address they have registered with the Ohio Department of Insurance, which you can find by going to this link:  https://secured.insurance.ohio.gov/Company/authlist.asp.     And you are entitled to have your sales tax reimbursed to the extent of the applicable law, which states: (f) If within thirty days of receipt by the claimant of a cash settlement for the total loss of an automobile, the claimant purchases a replacement automobile, the insurer shall reimburse the claimant for the applicable sales taxes incurred on account of the claimant’s purchase of the automobile, but not to exceed the amount that would have been payable by the claimant for sales taxes on the purchase of an automobile with a market value equal to the amount of the cash settlement. If the claimant purchase an automobile with a market value less than the amount of the cash settlement, the insurer shall reimburse only the actual amount of the applicable sales taxes on the purchased automobile. If the claimant cannot substantiate such purchase and the payment of such sales taxes by submission to the insurer of appropriate documentation within thirty-three days after receipt of the cash settlement, the insurer shall not be required to reimburse the claimant for such sales taxes. In lieu of reimbursement, the insurer may pay directly the applicable sales taxes to the claimant at the time of the cash settlement. Ohio Admin Code Section 3901-1-54(H)(7)(f). Best of luck to you.