Unless you're talking about something else, it's not a Wal-Mart bike, it's a Currie bike. And you must have some problems with the bike. I've had my ezip for almost a year and I ride it daily. I hardly ever pedal. I weigh 200 lbs. It goes up gentle hills without pedaling. Steep hills with easy, minor pedaling. 18mph on flats. Never had a breakdown. Not even a loose screw or flat tire. I drive on a lot of rough gravel and dirt roads with way too many bumps. I wasn't aware that it was possible to put a battery in backwards, but even if you did, of course it will blow a fuse. The throttle is no different than any other throttle. If you let off a motorcycle throttle, it stops. If you let off a car's gas pedal, it stops. Even after a year, I can still go at least 8 miles on one battery fully charged. I sometimes fail to recharge after a ride and ride it again the next day even though Currie recommends charging after every ride, no matter how short or long a distance you rode. The battery pack weighs 18 lbs. Yes, you could lighten it up a LOT by using advanced lithium ion batteries, but the cost is astronomical. Lead-acid batteries are still by far the most economical. But if you had the funds, upgrading to lithiums would make the ezip a very very good bike. Most of the $1000+ bikes out there have no more range than the ezip does. I paid $150 for my bike brand new on clearance at Wal-Mart, and it was even assembled by Wal-Mart employees, so I guess I got lucky. Still, my only hangup is the loud whirring sound of the motor. It is NOT silent. Here's my bike on Youtube:
http://www.youtube.com/watch?v=Zs7wt50pnmE