6 months waiting for an invoice

I have previously loaded a complaint for my billing being incorrect - ref no: 634023, 805238, After 4 months of weekly complaints on Hello Peter - Sifiso finally came back to me and provided some type of feedback - though not satisfactory, I then requested an invoice from him to establish as to why exactly they are still billing me incorrectly - as they are still billing me for a contract that had expired and that was cancelled as from 01 April 2015. He said he would come back to me, our first interaction was on 22 September 2015, and I'm still waiting - ever since my contract was moved to Autopage from Nashua Mobile - just once I would like to at least receive an invoice, they simply just debit my account and I have never received an invoice from them, and after numerous request - I am still waiting. The call centre is totally unable to assist as they say these queries should go the billing department - however they are not permitted to transfer the call to the billing department - so again I am stuck - 6 months and I am yet to receive an invoice, the service received from Autopage is pathetic to say the least.... I will never do business with them again and suggest you don't too!