I bought a '54 plate MCS convertible from a local dealer 3 months ago. Last month, I had a couple of tyres fitted, and 4-wheel alignment done. They spotted that the front wishbone bushes were worn, said to get them changed, then bring car back.
Car was still under warranty, so supplying dealer got the local BMW specialist to replace the bushes, and also fix the airbag light (new battery cable fitted).
Yesterday, I took the car back to the tyre shop to finish the alignment. They noticed that the bracing bars that run from the sills to the rear subframe were loose. All the bolts were showing about 15mm of thread, and the one in the driver's sill had fallen out!
Looks like the specialist had dropped the bars and brackets to feed the new cable through, and forgot to tighten the bolts afterwards.
If the tyre place hadn't spotted this, eventually the whole lot would've dropped off, and I dread to think about the potential damage!