Does not wan't to give full refund

I order a product from [URL Removed] She sent the parcel with the Post Office. Every time I went to check the track and trace on the Post Office website the parcel was not at my address yet. Because of the postal strike I didn't receive the notification letter saying my parcel is at the post office months after it was sent back to Sarah.<br> <br> Sarah refuses to give me a full refund as I no longer want the product. She wants to ship it back to her supplier and refund me the difference. This is unacceptable. She has my money and now she only wants to refund a portion to cover her shipping costs so that she doesn't get burned.