Cell C does not care

How long can it take to get a credit passed by Cell C for their own wrong doing? We are now nearing 4 months of complaining and still this issue has not been resolved, and to top it all off, now there is a lack of communication by one of their supervisors Luke Ludidi, after it has been confirmed in writing that a credit will be passed on our account and refunded into our nominated bank account. Clearly Cell C does not care about their customers or care to provide sufficient customer service. I request that the full credit that was agreed upon in writing by Luke Ludidi be paid into the respective bank account, that was provided to him, before close of business today 16/10/2015, as Cell C had ample time to resolve the matter at hand. I DO NOT want this as a credit on the contract. This was not our fault and why must we be held liable for the mistakes of the managing staff at Cell C.