Bought my 2015 M4 in May from an approved Used dealer up north of England let's say to keep it fair (ongoing case open), because there were none of what I wanted in the south near me.
October 5th water leaks past seals and damages sensors giving me first a diff error then a chassis error then the speakers cut out.
I called a central service line on the 6th after the first diff error, explained, they booked me into my local dealer to sort. On the 21st - over 2 weeks later. I was like er the water will cause more damage, they were like that's the earliest appointment. And no courtesy car.
With the chassis error the next day I was like nah, called again, they booked me into a slightly further dealer on the 14th, and in it went. Still no courtesy car available.
They diagnosed the issue and quoted £2k to repair, wouldn't be covered under warranty as seals are wear and tear/perishable, but to call the guys I bought it from up north, which is kinda fair. I called them, they looked into it and a manager said no.
I have complained to bmw themselves, 48 hours and I should have an update apparently.
It may all get resolved, but it's not a great experience so far.