AliExpress complaint: Returned parcel

I ordered an item which I was told had been delivered. It hadn’t been delivered nor had a delivery attempt note been left. AliExpress told me to contact the post office but the tracking number didn’t belong to the post office so then they told me to get a signed letter from the post office to they didn’t have the package. Ask a company who had nothing to do with a delivery to say they didn’t have it was the most ridiculous suggestion I have ever been asked to do. The seller then found out it was with CTT EXPRESS but there was no documentation or information as to which office it was supposed to be at. Even the seller, in FOUR WEEKS, couldn’t locate this package. AliExpress refused any claim I made even refused my appeal. I drove 30 mins to the main local depot of CTT EXPRESS and was told it had been sent to a satellite collection point. After two different addresses I got to the third depot and was told it had been returned the day before. Now AliExpress say I still can’t get a refund and I am left with no item and no money refunded. In my opinion it is up to the seller to ensure their item reaches the buyer, it is not my responsibility. The amount isnt much but now it’s the principle. Their customer service is non existent and all they see is black and white and can’t look out of the box and also use common sense.