Asics Running Shoe Toe Blowout at 20 Months

After about 20 months of use, a noticeable hole developed at the toe of the right shoe of a pair of running shoes I purchased through Marlin Spor's website. Believing that this kind of deterioration was not normal for that timeframe, I sent the shoes in for inspection.
I shipped the shoes to the company, but after their review I was told there was no defect attributable to the product itself, and my claim was denied. I cannot accept the fact that a visibly worn-through hole is being dismissed as user error with no accountability taken whatsoever.
I am asking Marlin Spor to either refund the cost of the shoes or replace them with a new pair to make this right.