Lion minds wanting me to pay more for software which was not helpful and I hadn’t used even after paying cancellation fees

Hey, I've had a bad experience with Lion Minds. I purchased a deal software to aid my daughter's study, but when we got home to install it, it didn't work on her tablet. I went back, where I was informed that the software works on both laptops and tablets. And we only had a tablet. The saleswoman misled me, and when I told them I wanted to cancel, they said I had to bring the software back, but when I got to their offices in Wonderpark Pretoria they have relocated,They contacted, and I informed them that I wanted to cancel. I paid a cancellation fee of R1200, but now i keep on getting their calls insisting that I must pay more.I don't feel like I'm being treated properly since if their product had not been useful to me.