Cell C bad service

Cell C handed me over for collection, my account is not in arrears, I even e mailed the latest statement to the collection company showing I am current, I have spoken to Cell C customer care about 5 times and still I get calls from the collection company to pay the money....I DO NOT OWE ANNYTHING...I HAVE BEEN HANDED OVER WRONGLY...PLEASE SOMEONE RECTIFY THIS...I AM GOING TO CANCELL ALL MY CONTRACTS....