Over charging of account

my contract had expired and i was upgraded, as per the Cell direct my new contract will be R529.00 per month, i recieved my first bill from telkom for R1597.00 which i imediately contacted the accounts department or 180 and a case was opened. i recieved a call at night and the gentlemen told me the extra fees was for the use of the phone which i told him was completelt incorrect, he advised me he would call me back, that was the 03 November, today been the 18 November i called back and foundthat they reduced my amount to R954.00 which i told the agent i refuse to pay, they now claim its porata usage, strange my contract was only activated the 30 November so how do they want to charge me R425 for two days usage? the agent said its for a full month of usage which sorry i only had for two days, plus how come was none of this explained as i would not have bothered to renew my contract with telkom.