I can confirm that my car is at long last fixed. No surging reported this morning.
She did not need fuel injectors (BMW were incorrect) or the rocker changed (Prestige Auto managed to use up a part) – the car needed to be re-coded with a new software update! Bit like an iPhone.
Will be picking her up tomorrow morning.
Thank you for your support and patience Idan – I am glad it’s all over.
Erin Brokovich signing out.