Make it possible to cancel online and retroactively give refunds on your website. You'll never see a chargeback again.
It seems many times people use chargebacks as a form of cancelling their account. Instead of logging in to cancel, they seem to think a chargeback will have the same effect.
I'm wondering if this is the same for other subscription merchants? Any tips to combat?
There really is not much you can do about this problem other than be thankful that you are not one of these people - imagine how hard the world is for them every day.