User Activity

Ordered a Wheelbarrow but it came minus the wheels and handle.
I sold item to buyer on 19th February 2021. I was late sending item to buyer due to a family anniversary i.e. my mum's 10th anniversary (this is not an excuse, it's the truth). I put a Royal Mail Special Delivery by 1pm on polylope and uploaded track...
Buyer said she received a grey Royal Mail card yesterday with a fee to pay of £8.15. She refuses to pay this. Buyer says item will be returned to me. I do not accept returns.
I also posted item to her at the weekend, which she received today. Buyer says she received item but had to pay £8.15. I don't get that as I posted item via Royal Mail Special Delivery Guaranteed by 1pm. The tracking number was on the parcel as well.
Buyer wants to know what is happening as she has not heard anything.