Contract Not Cancelled But Been Billed

Good day the call centre contacted me in february 2017 selling me a modem and a sim card. i Have received the goods but i had 7 day cooling off period and i cancelled the contract and asked them to come and pick the goods. i only reakised two weeks ago that i have been billed like R2000+ for that contract when i wanted to apply for a new line on my business. i logged a dispute on 28/12/17 and to date nothing has been done .My case number is ********** 9. The reason i need it sorted urgently is because i need to apply for a second line on my business and that outstanding amount is not allowing me to do so.this is becoming frustrating as everyday i call and im being told that they still working on it.My contact number is ********** 943 .Id No ********** 218084.Thanks