Doesn't sound right re the radiator but try driving in comfort mode and see what happens.
Hiya
Well, computer guy never showed up, last time i waited nearly 3 weeks on him, he has all the MB software and tools so worth the wait.
So far since making this post, Ive replaced outside ambient temp sensor, and the inside ambient temp sensor, air filter, pollen filter, Start/Stop Module,/Battery , new thermostat, all genuine Mercedes parts.
My start stop is working as soon as I start the car, and it works right away, but after a few hundred yards it switches itself off.
It has been much better since changing these parts and its only sticking occasionally, I'm hoping it just needs codes cleared now.
FYI - Parts Info
Start Stop module/battery - Dingbro £97 / MB £168 includes vat - both modules made my Hella
Outside Ambient Temp Sensor - MB Part £30.40+vat
Inside Ambient Temp Sensor - MB Part
£18.10+vat
Thermostat module - Dingbor £110+vat / MB £75 includes vat.
Gearbox Service Parts - Genuine MB
Oil sump (filters built into sump) £130+vat
Transmission oil 5 litres - genuine MB - £55.71+vat / 1 litre - £17.69+vat (6 litres required)
New Stretch bolts - Genuine MB - x10 £15.50+vqt
Overflow pipe - Genuine MB - £10.10+vat
Guide Tube - Genuine MB - £1.35
2018 C Class AMG Premium Plus Night Edition Cabriolet parts bought from Mercedes Benz of Glasgow (smart)