Advertising stock and selling when they don't even have it!

I purchased some lures (quite a big amount of money) on line. They had advertised them as in stock. They emailed me the invoice, I did and eft and then a week went buy and I heard nothing. Phoned and asked about my order? They are so sorry their system must have lost it. They are busy backing and will courier it immediately. An hour later they phone to say.. sorry no stock.. what must they do with my money??? I has been two week of phoning, emails and begging and they keep on promising the payment has been loaded but it just does not get done! It's ridiculous!