Post Office unwilling to release approved R5000 refund - is that not equal to *****ing?

In November 2019 I errouneously transferred an amount of R5000 to the Post Office account for postal box rental. After a lot of effort, the Post Office finally acknowledged that they have received the payment and approved the refund on 11 June 2020, document number ***. Despite a lot of assistance from a particularly helpful lady at the Post Office, the refund has not been released by the two people responsible for that, Messrs Martin Malati and Phinius Mashishi. Efforts to communicate with the supervisor of these two people, Mrs Koleka Qambata, has also been unsuccessful. What do I do now?