Unkown Cell-C Airtime Billing

I reported this problem on of the Cell-C airtime that is being billed on my statement every months it is been over 4 months now and i have all the statements with me, when i wrote to Hello Peter they responded saying they will deal with the problem immediately that was on the 28.03.2015, up to so far they are still billing me the airtime that i don't even use ,because i use MTN,instead i got a message to pay R132.75 for my installment if i don't pay it will have a negative impact on my credit profile, off which i paid more that that bcause my account it is less than R600.00 the outstanding money, instead of fixing my account i receive messages that threatens me about my credit profile, i really need help here the interest on my account it part of the airtime that i dont even know the person who get benefits for that on my account, i have never experience such a bad thing being billed for something that you dont have, it is very scary to me. worst part i dont even get help, i just wonder how many people who have same problems ,who dont even have a voice to shout, no email, no phone to contact you no customer service that you get even when you call them