Adekil: I did mention the mode fault and they said they'd take a look, time permitting (apparently the software updates to be applied during the service were goiing to take 2 hours, even though the service itself would only take 1). Car is ready after service (2 hours after it went in) and they supposedly didn't find any faults, but the car is cured. My car is running 10% thirstier post service, and the oil likes to be a little cooler - 90C rather than 94/95 when the car isn't being pushed.
Sport acts like Sport should now. Perhaps the extra thirst is because true Sport mode actually has an mpg penalty i've never experienced before by leaving it in Sport and actually getting Normal? Or maybe it's more to do with running a bit cooler?
Did the car fix itself inadvertently as a result of other software updates fixing a clash, or did they fix it and deny fixing it? I don't know, i'd like to think they wouldn't lie to me about something like that.