Incorrect Ring Size / Ridiculous Lead Time

I ordered a wedding ring from Unbreakable Man in December of last year, this was over the festive period and such received the ring in early January. The ring was the incorrect size, due to them using half sizes and stating that the are full sizes. I made an inquiry with the Admin department and was told that their sizing is incorrect and that I would need to pay a handling fee for the collection and shipping of another ring. I disputed this, even going so far as to go to a jewellery store and place the ring on a sizing stick and take a picture to prove that the size was incorrect. After much to and fro and a long lead time they agreed to change the ring free of charge. I was then told that they did not have stock of the ring in the size I required and that stock would only be in the country on 13 March. I said this be fine at long as I had the ring before my wedding on 21 March. I have sent many email and tried to phone the MD of the company to get an ETA or response as to when the ring will arrive but have not received any further correspondence from anyone at Unbreakable Man! This has become ridiculous and threatens to ruin my wedding! Please make contract with me today!