DSTV MULTICHOICE *********** AND ******

I have a problem of people calling me early in the morning and late at night claiming that they are calling in behalf regarding me owing dstv R190. I am puzzled and annoyed because I cancelled my dstv long time ago, I think it's almost five years now. I received a confirmation then that the account is cancelled and they stopped debating in my account. Why all of a sudden I'm receiving this harassing calls , all this years I was not receiving any calls regarding this. When I ask what the money is for they are telling me about pro rata fee, why I was not told about it all this years only to be told now , I also requested a proof of what I'm supposed to pay for and I never got that proof, I won't pay for something that I don't know of, I cancelled dstv long time ago.