NEVER received item marked as 'Delivered', BUT seller didn't provide tracking UNTIL I requested it!

[dillsdprib]

Bought two items grouped as one shipment (April 15, 2020) & seller NEVER provided a tracking number for the transaction (See screenshot)!

Transaction was paid for on April 15th & seller marked item as shipped on April 21st (oddly, order details indicate 'Estimated delivery Wed, Apr 22).

Contacted seller today (SUN, 4/26/20) to ask if they happened to get a tracking # for the shipment & they wrote this, " I have the tracking but that's why I dont do refunds because then you have nowhere to issue a refund tracking is 9================="!!! Now what exactly did the seller mean by that?? I never questioned them why they never entered a tracking # in the 1st place (even though I provide a Track # for EVERYTHING I sell on Ebay!) 

I took the track. # seller sent today, on USPS site & tracking shows the item was delivered on THUR, April 23rd, BUT I NEVER RECEIVED IT!  I didn't contact seller yet about that, so I'm going to contact my local PO tomorrow to ask if item was possibly delivered to wrong address (happened once before when my PO claimed item was delivered & I never received, because they admitted it initially was sent to wrong address!).

So my question(s) is this?...

How would I know WHEN to expect the package when there was no INITIAL tracking provided? Who is at fault if I never received or even receive the package (based on the fact there was no way of my knowing of looking out for delivery, even though tracking indicates 'Delivered')?

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