High street seller on eBay outlet store not refunding after confirming a return - England

Hi all, Not sure what I can do.

I purchased an item from a hughstreet store, via their official outlet eBay store, I contacted them regarding an issue after 3 months and was told there was a year warranty and I could return.

They arranged collection and they confirmed receipt and that refund would be processed within 5 days.

I was then told due to being purchased over 3 months ago, they could not process the refund via eBay as the system would not allow this, they requested me to open item not received case with my bank and pursue a refund via that method.

I said I am not happy with this as a resolution, I believe this is not an issue for my bank and it is up to the seller to arrange alternate refund via cheque or bank transfer. (this is a massive high street store everyone knows) and this is unacceptable.

They refused and said this is the only possible way.

I contacted eBay who say this is a matter between me and the seller as I did not return via the proper returns process. (I could not due to being greater than 30 days, but there was a 1 year warranty) They suggested to tell the seller to refund via Paypal.

I told the seller I would accept a PayPal refund.

Seller said they can only process this if I show proof that my bank would not allow me to open a chargeback claim.

I showed proof that my banking app would not support a chargeback as not of the categories fit where a seller has received a return but refuse a refund.

I told the seller refund me by X date or I would issue a MCOL

X date has passed and there is no refund. This has been going on for over a month. Unfortunately it looks like I was scammed by a massive company.

Is there any suggestions please? thank you