Cell c don't care about they customers

I was a customer of cell c. I phone the call center to inform them before my debit order Day is due I will be changing my bank account which they must deduct from my new account. I never noticed they don't deduct because I did not have cellphone banking and haven't received notification. So eventually my account went into a arrears. They hand my account to Hammond and Pole .immediately I made arrangements and start paying them.A month after Nimble collection phone me that cell c hand my account to them.I did pay for six months for Hammond pole .After Nimble tell me I have to pay them I start paying them. I make arrangements with them as well which I was outstanding 2000.. cell c is still appearing on my credit score I don't even own them ..I start paying nimble they inform the credit i don't pay but I do pay them my score drop with 22 points .