We have had situations where the parties agree to go to mediation we assign a mediator but then the school and parent hire an outside mediator  Or they contract with an individual that we do use as a mediator but is not the mediator that was assigned

We have had situations where the parties agree to go to mediation, we assign a mediator, but then the school and parent hire an outside mediator.  Or, they contract with an individual that we do use as a mediator, but is not the mediator that was assigned on our rotation basis. They leave our appointed hearing officer hanging, failing to respond to the mediator’s attempts to schedule the mediation.  Or, they get an SEA appointed mediator, don’t respond to attempts to schedule the mediation, but then report to the hearing officer that the mediation can’t be scheduled until at least 90 days beyond the current resolution period. Have any of you had any issues like this happen? How long can the parties extend the resolution period?