How can I "verify" what he has done - who would be the mediator if I don't agree with what he invoices?

Used paperwork from a consultant which charged the seller $3500 for his mediation.

The title company has already sent out their interpleader letter and a resolution is required by 6/10 before its sent to mediation.

My parents sold a property with a solar system on the roof, and now the new buyers, are demanding the go to mediation in regards to who owes for the repairs.Thank you @sandratatum

If there were a dispute over commission, the standard of practice in Wisconsin is first mediation and then if an agreement is not able to be made arbitration which would be binding.  

It likely spells out mediation, etc.

At least run this by a lawyer, its worth the few hundred bucks and easy to get on the wrong side of the law (I have done court mediation including landlord/tenant).Jon

• Consider Mediation – Ask your neighbor if they would be willing to go to a professional mediator to try and resolve the issues. • Hire a Lawyer – If nothing else has worked, then it’s time to hire an attorney and deal with the issues legally.

Have a clause that if any work needs to be done to the property then additional loan money would be given at interest (not sure what a good amount would be).Disputes would be handled through mediation, followed by arbitration.If someone wants to leave they have to buy out the other person's equity/debt. 

The water mediation crew was also covered where they brought Servpro to do demo and set up fans everywhere to prevent mold growth.