AliExpress Refuses Refund After Returning Package

I placed an order through AliExpress, and the package arrived at the PTT office. However, while it was still at the branch, I decided to return it. Despite returning it, I haven’t received a refund, nor has my package been sent back to me. When I contacted them, they informed me that they wouldn’t be sending the package back, and no refund would be issued. If neither the package is returned nor a refund is processed, I will file a formal complaint with the relevant authorities.