Impossible to get a refund!

I ordered a game. After a week they told me that it was a refurbished product, it was not advertised as such and I requested a refund. I had to send my banking details three times in different formats. They keep on telling me the refund will be done in 6 - 14 working days, but the time has lapsed and still no refund. This is unacceptable and completely ridiculous. I WANT MY REFUND!