Hi Sarah
I had the full timing change just over a months ago and the noise returned within three weeks. Also the idle is now rather lumpy (almost like the timing is slightly out).
I emailed Elms in Cambridge a week ago.
" With great disappointment I have to report that after a month of trouble free motoring since the entire timing assembly was changed and with things were looking genuinely promising regarding the longevity of the repair/parts, unfortunately the cold start noise has returned with vengeance during the past week."
Customer service manager replied saying the info has been passed to the BMW regional manager and he will liaise with his technical dept. Still no word as yet from them on the next stage of this ongoing saga.
Paul