DHgate.com complaint: Refusing to refund

Hello,

I ordered a 4 in 1 car seat from the seller Windowplant. After 3 months the seat finally arrived. After inspecting the car seat I could tell it was poorly made and very unsafe. I did research and found it is a knock off of the Doona car seat stroller, it has been crash tested and is very unsafe. It can cause serious injuries or even death for children. I can not use this seat nor will I ever put my son in danger. After trying for over a week to return and refund, the seller messages back and says “this order is now completed thanks”. At first seller was willing to let me return if I paid shipping. I don’t understand how they are allowed to sell something so unsafe then not accept returns.. please help me in this matter. I am a single stay at home mother of a newborn. We have needs and I am not out of $240 and a car seat. I need this issue resolved and the seller is not providing help. DHGate is saying there is nothing they can do, that the seller has to approve a refund which they will not.