Billing Issues

We have been trying to sort out our account with Neotel since August last year when a product was sold to us which was not suitable. Neotel has managed to reverse most of the charges which were processed to our account but the account still has a balance outstanding because of the billing issues. I have been in correspondence with Sophia to try and resolve this issue but have not had any feedback from her since 30 March 2016. I am trying to get Neotel to clear this account and always get the same excuse that it is a process that billing needs to follow but there has been no change for a month now. How long does it take to process a request, especially a request which dates back to August 2015.