Bad service!!!!

Have bought a lot from them and was happy, but now I am finding that they don't have stock of something that I have already paid for and try to offer me something else. I said they should refund me, but a week later my order arrived with the something else in! When I went on the site to check my orders, they are all gone and when I asked about it, they said something about a system change. Make sure you have the product before you try and sell it!!!