If you're selling something shady you cant really reduce chargebacks. It's a part of business. I hope you have a solid bank you're working with that allows for high chargebacks. I'm sure they hit you with a rolling reserve as well to cover these. How high are they?
Never be afraid of chargebacks if you have the foundation set up. They can come in like crazy into your office, remain calm, and defend each of them the same way. Same day - don't let the CB notifications sit in your office while you moan about responding to them. Hire a girl whose sole job is to defend them. It's all boilerplate. Show your website's FINE PRINT explaining how theyre rebilled (feel free to print using a larger font) and highlight it, make it look like you took great care to put together this package for the bank. Most of them should go away unless you're being really really shady and someone from the bank checks out your website a second time and catches you doing something just plain wrong.