Issuers encourage filing disputes online or by telephone, perhaps because that doesn't trigger the legal protections which impose very specific performance requirements.
MIA, thanks for the advice. Until this dispute I never realized that disputing by phone or online has different legal repercussions to disputing by mail. This is excellent advice and I will definitely use going forward. I did wind up faxing over a statement to Chase's dispute department that I believe did fall within the required 60 day time frame for a dispute but unfortunately they had already found in the merchant's favor so all they could do was to reopen the dispute which is still ongoing. The annoying thing is this dispute is for a supposed purchase in the four figure range and the receipt I have documents the purchase amount should have been in the 2 figure range so quite a difference. This is why I am highly considering legal action at this point because Chase doesn't seem reliable with disputes.