Agreed. A response is sensible, but my personal view is always that one's tone is best kept professional, separating fact from emotion. The points the letter makes are good. The goal is presumably for the matter to be escalated, as Edward is probably just a customer service rep instructed to respond to complaints with pro-forma points.
Referring to "thugs", "monkeys" and "responsible adults" doesn't really add any material information to the letter - the same points can be made without playground insults, and in my view a letter that sticks to the facts might be more likely to be taken seriously and escalated up the chain, which is presumably what you want.
That said, it's your name that's going on the letter, so it's your choice what language you decide is appropriate.