To calculate the overall star rating and percentage breakdown by star, we don’t use a simple average. Instead, our system considers things like how recent a review is and if the reviewer bought the item on Amazon. It also analyses reviews to verify trustworthiness.
The old product meets all the criteria for exchange but still the delivery boy will keep finding a flaw that is completely redundant and doesn't falls under the clause of exchange specified by Amazon services. Hence, the delivery boy will mention some illogical reasons and flaws and won't accept the exchange for the product.