Every A-Z claim going against me

Recently we’ve had around 10 a-z claims go against us for non delivery, even though the tracking for each order says it was delivered before the estimated delivery date and also has images showing the parcel being handed over and signatures when taken. I keep appealing them by sending over a message that includes the dispatch date, the estimated delivery date, the actual delivery date, the info about the images and also the signatures name. Even after all this info the a-z claim appeal get rejected. I’ve even contacted amazon and they just washed their hands of it and said I need to appeal the claims and they don’t have any access to the appeals department. Dies anyone have any info on how I can stop this as its tanking my defect rate as is making me lose £1000s in stock and refunds.