Weird noise after service at dealership

[chesticals]

Just bought my 08 135i last weekend. I had a pre purchase inspection done on it and they shop said it was in great condition, other than the horn not working. I put like 600km on it the first 24h of having it, no issues, everything sounded and felt great.

Previous owner said it needs an oil change, so i brought it into my local bmw dealership and got them to change the oil. We went and got lunch, came back about 45 mins later to check up on the car. Service advisor said its out on a road test. We wait like another 45 minutes at least for the tech to return with the car, then we pay and leave. As soon as im driving away i can hear a loud rubbing/friction-ey sound coming from underneath the car, increasing in pitch with the increasing speed. It sounded like it was coming from all directions but we pin pointed it to just behind the center console, on the floor infront of the back seats.

I take it back to BMW dealership and explain this, (4:45 on a saturday) they are getting ready to leave but they throw it up on the lift and run it while its in the air, and the only noise we could hear was from the diff, a sort of whirring sound, they put it back down and told me that it might be my rack and pinion, said they dont work on that stuff there id have to take it to a machine shop, then they sent me on my way.

What the hell. Dropped it for an oil change and now its has a awful sounding noise after an extended test drive.

Now its been four or five days and the noise seems to have gotten significantly quieter, but its still there. Do you think BMW will help me out at all? Are they in the wrong? Is this a known issue with the diff? Would installing an LSD essentially fix the problem? Is it even a problem?

Thanks

[sprp85]

Did you confirm miles in / out ? It should be on your service order.

Even with that, it will be hard to prove your ground on telling them there was no noise previously so be ready to throw down a hell.

Good luck

[chesticals]

I didnt confirm miles in/out but i have the service work order, ill double check when i get home