Billed R11 420 AND phone disconnected

I took out a contract with Telkom in October 2015, for an iPhone 6 on smart plan 50, for R450 per month. In January 2016, I upgraded from smart plan 50 to smart plan 100 (R499 per month). However on the 1st of March 2016 I was debited R8 920 by Telkom. I then reversed that debit order with my bank. Thereafter I contacted Telkom on the 1st of March 2016 to ask why I was debited that much. My query was logged with reference number ***8. On 15 March 2016 my phone was cut off by Telkom, even though I haven't received feedback with regards to the debit order. On the 17 March 2016 I proceeded to make payment of R513, which I calculated to be what I was actually supposed to be debited. I have been following up EVERY single day, however the call centre agents tell me the same thing, that the query is sent to their back (whom I cannot contact myself). Today on 24 March 2016, Telkom has debited me yet again for an amount of R2500. Call centre agent is unable to tell me the reason for the debit. This is my last resort, I have tried the call centre, social media platforms without any luck.