Telkom failing to receive communication

Telkom owes me a refund of over R500. Despite having been promised in February that this would be refunded within 7 days, I am still waiting. I have complained twice about it on Telkom's email complaints service. Twice I have received an email from Telkom in response, asking me for documents. However, when I email these documents, the mail returns undelivered stating that the mail box is too full to receive my email.

Effectively, Telkom has not been efficient enough to make sure that the channels of communication are open. Telkom, please attend to this complaint providing me with an email address that can receive the documents you ask for, and can duly process the refund with interest urgently.