Costco Mattress Delivery Service Cracked My Flooring And Denied My Claim

While bringing my new king mattress up the stairs the delivery guys dropped the mattress twice and dragged the mattress up the stairs stairs briefly cracking my laminate flooring pretty bad. I filed a claim, their person came out and two weeks later I get a poorly worded denial in a handwritten envelope. The letter is typewritten on plain paper, no letter head. They admitted to dragging the mattress up the stairs but say the mattress is too soft and light to crack my laminate flooring. I don’t want to pay an attorney to write a rebuttal but it’s possible I may have to replace 14 stairs and the 300 square foot loft because that flooring all matches. What do I need to do to rebut this denial or am I SOL?