Poor service level from Ali express

Good day, Any advice or guidance on the matter below would be greatly appreciated. I purchased a product through AliExpress, but unfortunately received an incorrect item. After several communications with the seller, the seller acknowledged that the wrong product was sent and instructed me to return the item via my local post office before a refund could be processed. I have already visited five different local post offices in an attempt to arrange the return, but unfortunately, I no postal office is able to do so. I have also investigated commercial courier services; however, the cost of returning the item is approximately 5–10 times the value of the product itself, making the return commercially impractical. At this stage, I am being told that there will be no return and no refund, despite the seller acknowledging that the incorrect product was supp****. I would greatly appreciate any advice on how I can resolve this matter or escalate the issue with AliExpress. Thank you in advance for your assistance.