Shocking service for advertised items that they do not possess and try to get you to buy something else that you do not want

I placed an on-line order and only a week later a gentleman phoned to say they did not have the stock and he tried to offer me an alternative item which was not even remotely the same. I then asked him to cancel the item and give me a refund. It is now 10 days later and I still get no response from my numerous e-mails... it is as if they have taken my money and disappeared.