Multichoice must refund me

I upgraded my decoder to a newer model at Nelspruit multichoice agency 27/03/2020 . The agent (David) told me to pay R599. I paid. I queried this because the decoder was under multichoice insurance. Afterwards multichoice confirmed that the decoder was insured and I shouldn't have paid. Multichoice must refund the R599. I have been trying to get the payment from them for 4 weeks now. Everytime between themselves and the Nelspruit agent I am getting the runaround of the matter is escalated, and they will get back to me. Which they never do. I spoke to Thombi 2/4/2020. Tholoselo 3/4/2020. I went to the agency and together with the agent spoke to the supervisor Lebogang. I spoke to Mpho 16/4/2020. This morning 23/4/2020 I spoke to Thobogo. Same story. It is being escalated, they will get back to me. Multichoice is *****ing my money!!!! I want my money back with bank interest!!!!