Debit order dispute

It's been incredibly frustrating dealing with this for the past 3 months. I keep having to contact FNB to reverse a canceled debit order from Netstar, and they charge me R40 every time! On top of that, I've also paid them R80 to try to stop it permanently, but it keeps coming back. I've contacted Netstar directly as well, but haven't gotten anywhere. Money is tight right now, and every cent counts. This feels like a total rip-off - I'm paying for a service that doesn't even work!