Sorry for bumping this, I've been away but I received a response from SuperShuttle--they were very apologetic and said they were refunding the prepaid fare and additional "tip", so about $70 total. No receipt for the $80 cash so there's nothing they can do, but still way more than I was expecting and brilliant customer service. Also, they're "investigating".

All in all kudos to SuperShuttle ^, hope the driver gets sorted out, and for future reference it never hurts to make a mental note of your van number in case things go wrong...

Thanks to everyone who responded!