Account Closed over 2 years ago, DSTV unit broken, charging me.

Over 2 years ago my DSTV unit was faulty. I ask for a replacement which I was told that I did not have insurance on the unit and I need to buy a new unit. I refused and told them to cancel my DSTV account. Now 2 years later they are saying I owe the money? I went into there sub offices, they have it on record that my modem is broken, but the person did not cancel my DSTV account, so I owe them money. What did I watch the DSTV on if my unit was broken. I have been phoned by there debt. Department and they won't stop no matter how many times I tell them I don't owe them anything, they even had the gall to say I agreed to pay them. I screamed at them and told them to listen to their phone recording and not to lie. Obviously the dept collector get paid if I agree to pay them. What a bunch of *****.