I have disputed (and prevailed) multiple times on credit card charges. One time several months after a cancelled hotel stay and the property continued to try and bill me. I had a ZERO balance statement but when management changed, they tried two additional times to charge my account. I have a stellar credit rating and have for many years so I am not 100% buying into this having any major impact.
It sounds like the aggrieved did try to initiate civil and reasonable negotiation but it is hard to negotiate when the other party shuts you out.