Cell C claiming I owe money & harassing my family

I cancelled my Cell C contract 3 years ago. I have the valid paperwork for this - nor have I been living in South Africa for 3 years as a work abroad - nor have I used Cell C for 3 years. They are claiming I owe R1000 Odd - it's got to the point where I have never received any kind of statement to my email - Cell C is basically harassing my family at which they obtained a number for - this is unacceptable by all means - I have the documents that I cancelled and I cannot understand that I owe money for 3 years which I have never used Cell C. I urge that Cell C stops harassing my family with immediate effect and provide me a statement with which I was was apparently using the network when I haven't even been living in the country.