Building a custom home and our builder is trying to stick us with an overage on an allowance that we weren’t expecting and he never got approval on prior to moving forward (per his contract, he was supposed to get approval.) We have disputed the charge, but he’s not having it and is threatening to stop work. Very much like extortion. If we pay his extortion to keep the house moving along, with an arbitration agreement signed as part of the contract, can we arbitrate the dispute post-closing?