Statements incorrect and no fixes done

Towards the end of January I was moving house and enquired that vox help me by continuing their service at their new address I spoke to one of the sales managers after his rep who signed me up had resigned( I did not know this ) and did not care to take my call. Eventually the sales manager was able to help by getting the cancellation fees waived and after 3 weeks or so my new line was set up. The problem is that now 3 months down the line I am still getting statements for 2 cancellation fees and still getting billed for my old address with my new address I have spoken to 3 different people to try fix this situation over the last two months and still nothing can be done. Yesterday one of them the man in the accounts department simply put the phone down mid conversation cause he felt like it and didn't call back. I have now emailed all 3 parties and messaged the sales manager who first helped out but no one is willing to get back to me and no one seems bothered to fix their mistakes in the accounts department. Who can I now speak to that can help me out this absolute disrespectful and horrible after sales service that I have been getting. I am at the point now where vox can come and fetch their router as they did no physical install and close my accounts and I will take my business elsewhere this is after I have recommended their services to multiple people. Absolutely terrible service from vox and their team..