being charged for something I didn't used.

Dstv self service is useless, I have an old decoder which I have not used that has dust in the garage. I was trying to upgrade my package to an upper package only to find that old dusty decoder, is on my profile not knowing it was that decoder. I selected it by mistake, now I have to pay for something that has dust and that I don't use it. I requested them to remove and delete it from my profile and they refused. I need help to not pay for what I did not use. I asked them to check when last was the old decoder connected or used, because it wasn't used for years.