Account cancelled

I had cancelled my WIFI account with the provider months ago. The person i spoke to was so rude at the end that when i asked him to send me confirmation he dropped the call. Now they call me telling me i owe them money. on top of that, i have not received data from them so how can i owe them money when they haven't been giving me data. That is pathetic business etiquette. Please be very careful when you sign with these network providers. i have been with MTN for more than 12 years and i have never had an issue like this.