2013 Fiesta. For months now the radio controls switch on the steering wheel has been playing up. E.g., up volume and it would change channel or not work at all. Went on forums but only solutions were spray with contact cleaner or replace switch. I only do short journeys and noticed after driving for 15 minutes the switch would work ok. Decided to charge the battery, took 6 hrs to fully charge. Now the switch is working normally. So I assume cold weather and short journeys reduce the control voltage at the switch. 

Hope it helps, Lez

Update: The radio controls are working and the stop start function has sprung back to life. So it looks that with Ford cars, short journeys discharge the battery to a point where the stop start does not operate, as the battery further discharges the radio controls on the steering wheel stop working. All I intend to do is fully charge the battery once per month. I'm happy problem solved.

Les