Have now taken my 159 in to Desira Norwich on 3 different occasions over past 18 months for minor warranty work. On each occasion they have been great - faults fixed immediately, excellent service and great attitude.
On the most recent visit, last week, it was to sort out excessive wind noise
and fit windscreen trim following new windscreen (insurance job) after stone chip and crack. Went out for a test run with technician (Jamie) to assess problem - not only is he an Alfa lover but is also a top technician. New door rubbers fitted plus windscreen trim with no arguments and no fuss.
I appreciate other people might have a different experience but credit where credit's due. I will check them out for the servicing if the price is right.