[MikeGMT]

All the following conditions have to be met for the Stop/Start to work. As you can see there is quite a lot of reasons it may not work.

• The car has not reached approx. 10 km/h (6 mph) after starting.
• After a number of repeated auto stops, speed must again exceed approx. 10 km/h (6 mph) before the next auto stop.
• The driver has unfastened the seatbelt.
• The capacity of the starter battery is below
the minimum permissible level.
• The engine is not at normal operating tem- perature.
• The ambient temperature is below
approx. -5 °C (23 °F) or above approx. 30 °C (86 °F).
• The windscreen's electric heating is acti- vated.
• The environment in the passenger compart- ment deviates from the set values.
• The car is reversed.
• The starter battery's temperature is below or above the permitted limit values.
• The driver makes sweeping steering wheel movements.
• The road is very steep.
• The bonnet is opened.
• When driving at high altitudes when the engine has not reached operating tempera- ture.
• The ABS system has been activated.
• In the event of heavy braking (even without
the ABS system having been activated).
• Many starts during a short period of time have activated the starter motor's thermal protection.
• The exhaust system's particulate filter is full. • A trailer is connected to the car's electrical
system.
The following applies to automatic gearbox:
• The gearbox is not at normal operating tem- perature.
• The gear selector is in M (±) position.

Just to put your mind at rest (maybe!) I have experienced all the problems you have expressed, except having a new battery fitted. About two months ago I had the Start/Stop Service Required message flash up for the first time ever. I put the battery on charge and everything resumed as normal for a few weeks, then the message re-appeared. I just ignored it this time and about a week later the Stop/Start sprang back to life. Know I just ignore the message and I am confident when the right conditions are met the system will decide to work again if the car is getting a few good runs. If the car is not getting used as much I just put it on a trickle charge every now and then.