Persistence will pay off. The better half's DSG Golf had a gearbox software update on 30/12/16 and it ruined the car. Slow starts and jerky gear changes but no fault codes so the local Main Stealer told us we had to accept it.
I wrote to VW UK and have been in dialogue for 3 months. Last Friday they sent us to another local dealer who also said it had no faults but suggested all sorts of options. I said do them all!!
Driving home last Friday lunchtime and the Mrs was smiling from ear to ear, she has her old car back. We were at the point of swapping it as she's had it 2 years but so glad we persisted. I'm sure if you get BMW involved they will help you. They certainly helped with my oil leak last year.
customer.service@bmw.co.uk
Best of luck