We sent buyer correct items as he requested 4mm blade, buyer received correct items for sure, we have record video and pictures showing buyer received correct two items. He asked for partial refund after he used it for a month. We told him to ship it back, he denied and threaten to leave a negative feedback, which he finally did.
Check his feedback, he loves to leave negative to other sellers, definitely his habit to ask for money back by threaten seller.
eBay should prohibit such eBay buyer, blacklist him.