Mr Delivery owes me a refund

My order arrived and it was completely wrong. I paid for things that didn't arrive and I paid for large meals and got medium. I complained and I got a R50 voucher which isn't even half of what I paid for and didn't get. I emailed Mr D 6 days ago to tell them that R50 is just not going to cut it and I still have heard nothing from them. I'm so irritated. They owe me money now and I will not give up until they give me a refund.