Yes, a TSP may file a transportation claim against your agency under 31 U.S.C. 3726 for:

(a) Amounts owed but not included in the original billing;

(b) Amounts deducted or set off by an agency that are disputed by the TSP;

(c) Requests by a TSP for amounts previously refunded in error by that TSP; and/or

(d) Unpaid original bills requiring direct settlement by GSA, including those subject to doubt about the suitability of payment (mainly bankruptcy or fraud).