REFUND - SHELL BULT, POTCHEFSTROOM

On the 17th of May 2019, I poured petrol to the value of R730 at Shell Bult, Potchefstroom. I swiped my card and the attendant said it declined so I gave him cash only to discover that the payment was approved on my card. I have given management my bank statements and all details to prove this and I still haven't been refunded! Instead, I have been sent pillar to post for almost a month now!!