Amazon doesn't help sellers deal with these kind of issues very well...the best thing you can do is try and proactively contact customers when they leave inaccurate feedback. It's tougher now that Amazon makes it almost impossible find the order associated with a product review, so sometimes your only option is to leave a review comment.
In terms of getting products reinstated, in your reply to the Seller Performance team, make sure you own up to any issues and clearly state how you would address going forward. Even if you think the issue isn't your fault, it's important that you take ownership of any problems as the business owner. I've had to contact Jeff Bezos' Executive Team as a last resort and that's worked for me a couple of times as well.