I d say there s something REALLY wrong and that you need to convince the dealership of that (a test drive ) and that THEY need to solve it PROMPTLY-use the word dangerous a lot

Also, you could suggest to them that continuing to drive like this may cause even more damage $$$$$$$$$$$. If you take this problem on yourself they will let you .
PS. you could take a quick look at the rear springs and check tire pressures