u/Hot-Nectarine9800

I sold a set of books for around £20, I originally paid £40 for all of them they were brand new I never read them they just sat on my shelf, I will admit I should have packaged them in a box but I did bubble wrap about 3 times just to make sure, when I sent them they had no bends but when buyer received them they had very slight bends to the front pages on some, buyer is now asking for a refund and to also keep them, I will be very much out of pocket and I’m not sure where I stand on this. Any help would be appreciated