Woolworths transaction

I would like to state the following which I think is against the law. I am at home with Covid. Decided to purchase my groceries online. Well, this is what they do. You make your purchase and the deduct the amount from your bank account. Then upon delivery they deduct whatever they dont have in stock and deduct another mount off your bank account. They then wait for you to contact them and you have to give them permission to contact your bank and instruct them to release the first amount back into your account. My initial purchase was done on the 14th of June, it is not the 23 and still I have not been reimbursed, which means that you pay double for your purchase!!! What about the customers that dont check their accounts? Does Woolworths then just keep quiet and keep the money?????