Checkers too money but no groceries delivered

I bought groceries of just over R600 on 13 July. Just before the delivery time my order was cancelled without a valid reason. I have not received my refund since then. I've sent several complaints on their app and also via email. They asked for proof of payment and I sent them but still nothing came through. They always tell me to wait 24hrs but it's been a month now. I want my money!