Taking money out of my account *******ly after I've stopped it numerous times.

I've had the worst experience. I haven't had reception on my wifi router for 12 months now. I've phoned and emailed to stop account. They have collected device more than 4 months ago. But they keep on taking money out of my account. I tried to stop it at the bank but still they take it out. I'm talking abou R1500 at a time. Every time I reverse the amount thy take it out again and I pay a fee for that every time.