Please check the old starter motor for a grey powdery substance/metal filings in the open part of the starter motor when removed from the vehicle. There is a common problem on this application of the Dual Mass Flywheel (DMF) breaking up causing failure of the starter motor. Another starter will not cure the problem, as parts of the damaged DMF will cause the replacement starter motor to stick and fail prematurely, failure due to DMF is not covered under warranty
And in the case of a Focus 1.6/2.0 TDCI Diesel Alternator, by entering AEK2814 into the Technical Support search, you will find the technical help below:
Ford alternator common wiring fault
Some customers have reported that the battery warning light stays on even after a replacement Alternator is fitted. The common cause of this problem is the battery live feed to the 3-Pin connector plug at the rear of the Alternator, this feed is either corroded in the plug or broken in the loom. The Alternator still charges, but with the battery warning light illuminated.
The Same is found for AEK3013, which is the Petrol 1.4/1.6 Alternator.