Tracked 48 does not update- seller not issuing refund

[emilia0405]

Hi, looking for advice

I ordered a large item on ebay which had to be returned as it did not match the description. Seller arranged collection and supplied a reference number for royal mail tracked 48. Item was collected on last Tuesday so it's been a week. The tracking number that Seller gave me says unable to confirm the status of your item. When I contacted seller, they are saying that they have not received item and that royal mail has not collected. I contacted Ebay multiple times and they said its the sellers responsibility and not mine but Ebay could not help further so I opened dispute with PayPal. 

Could anyone advise what I can do to get my money back ?

[tressygirl]

If you opened a case with PayPal  you have to stick with that now.

Do  not have 2 cases open at the same time, as it looks like you are after 2 refunds.

Now the PP case is opened only stick with that.  

@emilia0405 

[emilia0405]

Royal mail is not helping and seller is not responding.  I paid £164 for the item so worried. Can I do anything else to get my money back?