In warmer weather my S/S will start to operate when I stop at the lights 500yds away from home after the engine's been running less than 5 minutes from cold - so much for "
ten miles". Granted, the first couple of times it'll restart after a shorter period until the engine is warm.
I think the first line in the customer service handbook is "
Blame it on the customer"

. I got a similar response from the dealer when the car was new and the S/S wasn't working properly, only they tried to blame it on me not driving sufficient distances to recharge the battery and having a dash-cam 'draining' the power. They eventually gave in and replaced the battery and the S/S has worked to spec ever since (6 years!). As JR says, persist and don't let 'em off the hook.
I don't know about the current model but on older cars like mine, after switching the ignition off you can press the audio system power button and the radio will play for 20 minutes at a time. There's also a setting in the audio menu that will automatically cause the radio to play for 20 minutes after the ignition is switched off.