You don't always need to replace your rotors when you replace brake pads. Honestly it's good practice to replace both pads and rotors at the same time but it is absolutely not necessary. If your rotors still have enough thickness and don't look warped when you spin them, they are fine.
Also don't listen to Firestone, they are probably trying to sell you a bunch of shit you don't need. If your car was inspected by a BMW tech I would trust them before Firestone.
Doesn't sound like they checked your sway bar bushings, so I'm not surprised the issue is still there.