2025 Buick Enclave - Ongoing OnStar / Battery Drain Issue

We just purchased a used 2025 Buick Enclave Avenir. We too have found that our battery will not stay charged overnight. We are just day one into our purchase. The dealer has no idea when this part is available although our dealer did say that he would give us a rental car free of charge. He has no idea how long we will use the rental car. But our new purchase will remain at the dealership. We had no idea there were so many people out there with the same problem.  My question is why did the dealer let us leave knowing that this car needed the module.  They knew it needed one, knew they did not know when we would ever receive one and they still let us drive away!  What have others done as recourse? Is there recourse?  Other than a drawn out class action?  We will never br made whole.  This is fraud!