Under Armour Fails to Address Rapid Deterioration Issue

I purchased a pair of shoes from your store three months ago, and the inner back part has already come apart, causing discomfort and hitting the heel. I contacted customer service, and although the shoes were initially under review, they concluded it was due to user error. It's incredibly peculiar for a pair of shoes to deteriorate this quickly. Moreover, if it's user error, why hasn't the same issue occurred in the other shoe? Blaming the user and dismissing the matter hastily is not fitting for your brand. Good day.