Unauthorized debits from my account

In May i went to the CellC store in Malvern, Queensburg to do an upgrade on my current contract which expires at the end of August.I chose the Sony Experia E4 from the CellC catalogue which was expiring the following day.I signed the new contract & a consultant did the migration.The price on their system was higher than the price on the catalogue,I told her to cancel the contract as I wasn't prepared to pay the higher price.I asked her to change it to the old contract which she pretended to do & on two occasions she told me to come at the end of the month.My old contract is for R99/month on a Straightup 50 minutes,50 Sms & BIS(2G).In June Cell C debited my bank account for R276, July R174.99 & August R175.49.This is ***** as i didn't receive a new phone.In June i phoned CellC regarding this account and to terminate my contract at the end of August.To date nothing has been done.I spoke to the branch manager Sharita from Cell C in Malvern,she wants me to pay for the account & cancel the old contract.Please assist me as i am not getting any joy from the consultants at the store & the call centre.I cant be paying for something that i don't have and i want my money to be refunded to me.