I'm going to try and summarise this as best I can because it's quite long, but just hoping someone might have some advice.
And just to note, this was all well before Coronavirus/lockdown, contactless deliveries etc.
In summary:
-I bought an item off a private seller on ebay mid Feb costing £75
-Paid via paypal (linked to my bank account so money came out of bank, not credit card)
-Seller dispatched via Royal Mail recorded delivery. It arrived when myself and DH were at work, red card left in postbox that said 'parcel left near window' with no tracking number, date, time or any other info on the card.
-Checked all round the house everywhere it could possibly be, nothing to be found. Checked with neighbours too just in case - nothing.
-Checked tracking online, said it was delivered and signed for by my surname, with just a squiggle vaguely in the shape of the first letter of my surname. (Obviously not my signature)
-I called Royal Mail who said they'd look into it & messaged seller on ebay to explain what had happened.
-Few days later I get a letter from Royal Mail confirming driver admitted they had left parcel unattended and signed for it them self, despite it being a recorded delivery. Had been spoken to by manager and would not happen again. Also provided a photo of the front of my property to show where it had been left. Letter said ebay seller could claim a refund due to this.
-Sent all this info to the ebay seller who was very helpful and said she would open a claim with Royal Mail.
-Few weeks passed and after speaking with ebay they said to open a case with them so there was a paper trail and they could step in if needed. Did this, and ebay closed the case saying there was no evidence the parcel was left unattended and to ask Royal mail for more info. I did this and Royal Mail confirmed via email that the letter they sent with the photo is evidence enough for a seller to claim a refund through them.
Fast forward to now and I have opened cases with both ebay and paypal, both of which keep getting closed because the seller uploads tracking info that says it was signed for by my surname at my address. I have disputed both cases but basically keep going round in circles and having my refund denied.
Ebay say they can't help and to go to paypal because paypal overrule ebay.
Paypal say the parcel was signed for at my address so there is nothing more they can do.
Royal Mail say the contract is between them and the seller so they can't help me.
Ebay seller has stopped responding to my messages asking where she got to with her Royal mail claim.
I really can't afford to just lose £75, especially at the moment.
Anyone got any ideas if there is anywhere else I can go with this or do I just need to suck it up and accept that I've lost all that money through no fault of my own and have no item to show for it 
Many thanks in advance. 