Very unhappy with problem resolution

Physically visited the Randburg outlet looking for solar panel mounting clips. I had a sample of what I wanted. Reception said they had the clips and I paid. (Invoice 275448 dated 17 January 2022). Good service thus far. Went with sales staff to warehouse and found clips in stock were wrong size. A refund was promised via deposit to my bank account. I filled in the necessary form for the deposit and the lady to whom I paid copied me in on the internal refund request email. Its now a year and I am unable to find any record of the refund in my account. I have made two written follow-up and these have gone unanswered. I have the relevant emails. This is not good customer service. Not likely to deal with the company in future