(1) Timelines established in this chapter may be waived by mutual consent in writing of both complainant and local school district or other subgrantee. Such waiver of timelines shall be communicated within ten days to the appropriate division, superintendent of public instruction, by the entity named in the complaint.

(2) An extension of time limits applicable to actions by the superintendent of public instruction shall be waived by mutual consent of the complainant and the superintendent of public instruction: Provided, That if exceptional circumstances exist with respect to a particular complaint, the superintendent of public instruction may unilaterally extend the timelines for cause upon written notice to the parties.