Actually, they do handle Ongoing Harassment via tickets. What they won’t do is tell you what action is being taken with the person you reported (which you noted too 
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The real key to these situations is that if someone is harassing you, the first thing you need to do is put them on ignore. If it becomes a back and forth between two people, Blizzard tends to consider that a conversation and not harassment (with the exception of any inappropriate language being used which should be right-click reported).
There’s a lot of good info for the OP here: