Account problem not getting resolved

We have been trying to sort out our cell c account for almost 4 years now. They keep telling us that the account is in arears but we have sent proof of all payments numerous times, but the extremely educated characters that work in the accounts department just don't have the brain capacity to read our emails and understand and fix the problem. For a very long time we have been paying the acount every month but still don't receive any data as per the contract. So in actual fact they are in breach of contract because of their mental incapacity to actually resolve the issue. Please help to sort this out. I am seriously over Cell C