EDIT: Blizzard delivered the smack down to me (rightfully apparently). Apologies to Arenamaster as I jumped the gun.
I assumed he had sent back the CoD mail and kept the rest - this was not the case. Instead, the CoD mail had returned automatically after three days (which I learned is expected behavior if the person does not open it).
Additionally the GM that responded to my ticket mentioned that the other mail was still sitting in their mailbox - again expected behavior since it had not been the 30 days normal mail takes to be returned.
Finally, the GM provided the most polite smackdown I’ve ever received, stating that they did indeed review chat logs and found that I broke two rules, one being advertising in LFG and the second being naming and shaming and pointed out that I may have affected Arenamaster’s reputation unjustly.
So all in all, apologies to Arenamaster for my misunderstanding, which I’ll be making sure I rectify in-game as well as here. Also if they do log on soon I’ll be sure to give them the kit at no cost.