Account closure poor service

I have phone contract with Telkom that I want to close and I have called and even went to their store to request a final invoice so I can make payment and close the account. However, I have received little help on this - I would speak to an agent and they reassure me that they have flagged this on the system and they will send me the final invoice but have not received it yet and this was beginning of the year when I requested for it.

This is frustrating because this poor service is wasting my time and not acceptable.