Cell C double bill me for my handset

To Whom it may concern, After a month of battling with Cell C billing department and receiving a letter from them that they corrected my billing I just received a call from Cell C stating they will deduct my full handset amount again. I have settled my previous contract and taken a NEW contract now Cell C wants to bill me the full R9000 for the handset where I should only pay R945 per month for 24 months. I want a manager or someone high up to speak to as the people handling this issue have NO IDEA what they are doing. If this issue is NOT resolved today I will go and open a ******** case against Cell C. I have all the communication proof on email and cell c still can't seem to get it right.