Unfortunately there are more satisfied owners than dissatisfied owners. That being said, keep bothering them and of course settle down, think out what you're about to say well ahead of time. Whether you're venting here or yelling (I mean talking) to the customer service reps at the 1-800 # or the dealership.
After reading (and re-reading, and reading again) what you wrote it seems like you've had your car since April and only put 2500 miles on it. Is it rarely driven or do you drive it about 10 miles a day? #1 - reading the forums here, it looks like there was a bad batch of batteries as you aren't the only one who this has happened to.
Keep bothering them to get your money for a rental (check if you have rental on your insurance policy too). You might have it and not even know it.
If this is the only problem you've had, it isn't really that bad even though it seems like it at the moment. You wouldn't give up on walking just because you stub your toe.
I have 2 Smarts -
#1 - Almost 20,000 miles and no problems
#2 - 5,000 miles and no problems - knock on wood for both
Good Luck.