Billing me R2700.00 on a closed contract!!!!

I have now been on the phone the past two days with your call centre in regards to the billing <br> You are sending me. <br> I had originally opened the contract with Nashua mobile in July 2014 for a closed contract which <br> Stipulated that I pay R359.00 a month for a certain amount of data, certain amount minutes and SMS's<br> Before I would be automatically softbared. I do understand that the billing would not be accurate <br> And could be able to exceed the amount rendered. When with Nashua mobile this would never exceed <br> More than R100.00 before I was softbared.<br> The first month that you had taken over you have sent me a bill for +- R1900.00 as you can see on attached<br> For the December month. Due to your negligence you had left my contract open without my softbar limit <br> Without my consent and you want to make me liable for the amount due. <br> To my knowledge that is a breach in my contract and *******. Yesterday I have spoken to your consultants <br> Getting bounced around from one to another for 33 minutes at 14:30 with no joy. <br> By billing me this amount you have clashed with all my other debit orders putting me in the rear with my other accounts giving me a bad name!! YOU WILL PAY FOR THIS!