A-z claim, defect given even shipping label purchased from amazon

Can any one from amazon help plzzzz

I did purchase sign for delivery label from amazon, item lost by courier said by amazon but full refund issued to customer for the Order ID: # 203-0661121-3943548 . A defect has been given to me as well, effecting my account health. i did appeal but got rejected saying courier lost item during transaction although it was sign for delivery and courier is Royal mail. There is no fault from my side as i did purchased shipping label from amazon and dropped item to post office and got lost during transit.