Reversal dispute

Good day I'm writing this with a very heavy heart. I'm a mother and provider for my kids since I lost my job. I'm a sassa recipient on a monthly basis and I went to Sunshine cash and carry for monthly groceries. I swiped the sassa card for the amount of R840 which said it was a reversal and declined. They told me to bring the statement from sassa to show that money indeed left the account. I did so. It has been a whole month, calling, no one giving me proper info as to what maybe the problem. If this is their way of making people forget then this is not the business for the people. How does one forget R840 when I don't have money for my kids lunch. Sunshine has that money and they refuse to release it. How does R840 take to clear on a account and refund the money? Surely not a month Sunshine I want my money back. I need that money for my kids not for you to keep it