What I do with situations like this is contact the Attorney General in the state the company is located. In most states, that generates a nearly immediate letter from the AG requiring an answer by a company official...CEO, COO, etc. And they are required to answer the AGs questions. So it takes them several hours to gather the info and kind of pi**es them off having to do it. So they don't like it. It's rather satisfying.
But I digress...usually the threat of contacting the AG will get them to do the right thing and honor their verbal contract or in your case, written contract via the email. Might be too late for you as it's now moot since you cancelled the order.
JMO...also, rules change over time and different states have different rules but it's worth the effort to check online with your states AG's web page to see if they have a complaint form.