Wrong product in online store and still no refund

I purchased a Blue Sky Thermal Biner Mug online. When it arrived it was not the product on the store. I complained and was told I would receive the correct product. After not hearing from them again, I inquired again, only to be told that they do not stock the product I ordered. I also see they changed the product on the shop(I have a screenshot of the original order). I was then promised a refund and that the product I did receive would be collected. I also made it clear that I need the money to buy a different mug by Easter weekend. Nothing has happened since and I have not received any refund. I even have all transcripts of the conversations about this. This is completely unacceptable.