Your Dealer has nothing to do with this. Looks like GM Finance is running circles around you. You owe money to GM finance and not the dealer.
GM Finance is looking towards poaching your Acadia back so that they can sell it on higher price. You can buy it anytime before your lease ends as per your agreement. Talk tough with GM finance.

GM Financial Stops End-Of-Lease Purchases With Non-GM Dealers
Participating GM dealers will get priority.

GM is very notorious. They have banned selling your leased vehicles to one of their rivals or online dealers from July-1, 2021.