You should lodge a complaint with BMW NA customer service line. Although each dealership is independently owned. BMW NA will step foot into some situations where the reputation of the company is harmed.
You should also to speak to the GM (General Manager) of the dealership, not the "manager" . The person , "Alex" may had just been a floor sales manager.
This is one reason why I treat all car salespeople as crooks. They will through their teeth to make a sale.