Just keep paying us for parcels we wont deliver

They had my parcel since the in December. They kept telling me that they were delivering the following day for over a week. I then informed the book shop, they sent the replacement item and insisted on using UPS as the courier. The replacement books also arrived to UPS, and now UPS want me to pay for them even though they were sent to to replace the first ones they lost which I had already paid for.