If your Warranty is a BMW AUC warranty I would talk to your service manager and explain the situation push and as they replaced alloys yet clearly didn't check anything else??
If your Warranty is by other's (warranty Direct or similar) I would ask your friendly garage to talk to them on your behalf, garages do better than us.
I am attaching a page from the BMW parts catalogue that shows an exploded drawing of your rear suspension (one side) item 11 is the lower front arm of the rear suspension, if that makes sense to you, it could be slightly bent or the bush at damaged or worn prematurely due to being twisted slightly. That would give the out of alignment reading easily.
I would think the arm is in the order of £30 to £50 plus fitting at your friendly garage. As a comparison a full rear suspension replacement kit for both sides of my X5 was £250 plus 4 hrs work for myself and one of my sons (younger and bendier) then £100 for alignment (rear tyres are £250 a side for mine so worth the effort)
I am a bit OCD (well a lot) when it comes to the grubby bits underneath that make my car go where I point it and stop it when I need to so I would make it all as original settings.
I hope this is a help
RealOEM.com - Online BMW Parts Catalog.pdf
The Lower arm was out by 22 seconds (0.006 deg)...he said it was so little, but the machine is that accurate it picks it up and it gets reported! Not sure how bad that is?
I have comprehensive extended warranty that says it covers suspension below a certain mileage....however, I have an £100 excess, do depends on what it would cost at a good independent (Couldn’t imagine I have the gear to diy).
on the report it says O/S/F lower arm...which I think may refer to offside front? If so, not sure how the rear damage could have caused that (given it was more a very slow speed swipe to rear panel and wheel)? Maybe just a bad pothole or result of kerbing?
Or maybe O/S/F means something else?
Wow! the alignment was way out...as Dave quite rightly says, it may be worth replacing any suspect suspension components to correct it all but in the meantime I'm now it has been dialled into where it should be you will definitely notice the difference in driving.
Thanks for posting the printout
Looking at those readings you should be feeling a difference as well as having reduced tyre wear probably get some improvement in MPG as well. Following your comment that the car was hit on the rear and the fact they cant get full adjustment I would seriously consider a suspension rebuild as something is either badly worn or damaged. The job is not expensive and is a DIY task if you feel up to it the results will make your car drive like new again,
Good that it is almost sorted