Nothing in this part precludes:
(a) The compromise, suspension, or termination of collection actions, where appropriate under the FCCS, or the use of alternative dispute resolution methods if they are consistent with applicable law and regulations.
(b) An employee from requesting waiver of an erroneous payment under 5 U.S.C. 5584, 10 U.S.C. 2774, or 32 U.S.C. 716; or any debtor from questioning the amount or validity of a debt, in the manner set forth in this part.