MTN - refusing to port number to pay as you go

I have been trying to convert my month to month contract to a pay-as-you-go contract since the 28th of June. Whenever I phone the cancellations department, I get told that they cannot do it as there is a ***** block, they tell me they will investigate and get back to me. Not ONE person has phoned me back. Today I got put through to the ***** department and they told me there is no block on my account, but cancellations will still not process the move to pay as you go. It is now a month and a half later and my contract has still not been converted. This is absolutely ridiculous.