The criteria for the service warning lamp is a combination of cold starts, mileage and number of days since last reset.
This is the reset procedure for 2017 MY,
Turn on ignition without staring the engine by holding the push start button for 2 secs.
Press and hold down the accelerator and brake pedal at the same time.
After approx. 3 secs something like 'Service Oil Reset in Prog' is displayed.
Continue to hold both pedals down for at least 25 secs or until the display reads 'Service: Oil Reset complete.
Release the pedals and turn off the ignition.
If it doesn't work first time, try the procedure once more.
I hope this does the trick for you!
B-Max Titanium 1.0 125bhp manual City Pack.