If they had no stock item, they should have cancelled and refunded you the money.

You need to look at the dates when your item is supposed to arrive.

Once it goes past the date, it is late and you can go to ebay for your money back.

This is what you need to do if it runs late.

Go into your 'My ebay' section, look at the item and there should be a drop down section where you can tick "My item did not arrive".

It will open a claim with ebay.

You need to do this within 30 days.

Keep watching your claim and if the seller offers anything or asks you to close the claim, don't listen to him.

Get your money back. Ebay will make the seller refund in full.

Here is a link to help you make a claim.

Getting help with an item that hasn't arrived | eBay