Momentum BMW

I bought a brand new 2023 BMW 740 about 3 weeks ago. I drove the car and could hear a squeaking sound. (I thought it was the brakes) I called in and asked when I could bring the car in for service and explained the noise I heard. I was informed that they did not have any loaner cars and to come in the following week on Monday to drop the car off. I got there and all they had was a 5 series... no shade but if I turn in a brand new 7, id like something a little more comparable to my car. ~ I didn't hear from them until I called them on Wednesday and was told that it wasn't the brakes but instead the rear differential that was squeaking. They now have to replace it and the part has to come from Germany because there are none in the US. They aren't sure how long it'll take to come in. I came into the dealership after not hearing from them by Friday and demanded they give me a different car as a loaner and explained that Im not even comfortable in a car with a major component that's defective. Fast forward, now we are on week 3 of not having my car, they still don't know when the part will be in and to trade in the car in that I drove for less than 2 weeks, the trade in value is 84k and to get me into another car, I need to come up with 15k. The entire process is one big ball of frustration. ~Guess I need to contact an attorney at this point. Initially the service was great, now all I hear is there is nothing they can do. I’ll never buy the BMW brand again. I’m definitely going back to Benz