Purchased a refurbished laptop from Microcad with...

Purchased a refurbished laptop from Microcad with a windows 10 product key on back
Could not scratch grey area to reveil first few digits of product key. I finally revealed the product key to find it damaged, 2 digits where not legible. As their form of customer service they told me that I damaged it and have to purchase another product key for $30. I guess that's how they make extra money. Poor customer service. Last time I shop at Micro cad.