Struggling for 2 weeks to get our refund back

This pet shop is absolutely worst ever. I will never go to them again. We bought a ****atiel from them about 3 weeks ago, then 2 days after we took him to the vet and found out that the bird is under weight and the cage we bought we were told by the shop assistants that it was okay for a ****atiel and then we found out its actually a budgie cage, went back to get a refund for the cage and now 2 weeks later we still don't have our money and all the owner can say is "oh I am very sorry from the bottom of my heart" and that he cannot do anything about it.