Leroy Merlin false advertising and no refunds

I went onto Leroy Merlin website, and seen an item, according to the site, this item was in stock and there were 155 pieces in stock. I proceeded to place my order online, for a delivery which was meant to come 4 days later. I did an instant online payment, using one of their instant options (Ozow). a few hours later, I get a call from a lady (cell phone number) who tells me that there is no stock of the item and even the supplier does not have stock so they have to cancel my order and return my payment. She ends the call without asking for my details. I have contacted Leroy Merlin who tells me I have to wait 7 working days for my money, I refused, they then asked for proof of payment and banking statement, which I sent, and then got no response from them. Clearly they intend to make me wait the 7 days even though they said they can do an EFT. Worst of all, the item is still listed on their site, saying stock available. I refuse to accept the low level of service, and them trying to cheat me and collect interest on my money which is rightfully mine, and by them taking so long I am now unable to purchase the item at another store. Thus I write this so that others know what this company does, and proves why their items are lower cost. I will be taking this to a regulator as well to seek further assistance