Unable to secure a refund for a debit order

I settled my account with RCS on 22 August 2015. They then deducted an amount of R932.37 on 25 August 2015 via debit order. This amount was an over payment which needs to be refunded to me. The service and knowledge of the staff at RCS is shocking. On 6 October 2015 they requested my banking details and proof of last payment. Why I needed to provide proof of a debit order they initiated is beyond me, however the requested information was supp**** on 9 October 2015. They then requested a copy of my ID on 16 October 2015 which I supp**** on the same day. After a useless call to the call-centre I received a mail on 18 November 2015 requesting all the information I have already supp****. I responded by refusing to re-supply this information and requested contact information of a senior manager for which I am still waiting. I received a mail on 17 December 2015 now requesting proof of payment for the settlement amount made on 22 August 2015. Not sure why they need this proof as it was the debit order which was the over paid amount. The fact that these requests for information from me comes in drips and drabs shows the level of incompetence at RCS.