I'm probably going to repeat a few things, but this seemed easier than responding to multiple comments below.

For one - call the police. Note the dates and times of the calls, and give them as complete a "history" as you can of what was said to you during the calls. Hopefully they'll be able to view the phone records and at least get the person for making threatening calls.

For two - I wouldn't order from this Pizza Hut again, just to be safe, unless you've been using them for years without a problem. As unfortunate as it is, some people in the food industry aren't grown up enough not to exact some form of petty revenge.

For three - it's good that you're reporting this to Pizza Hut as well, as they should at least attempt to work with the Manager / Regional Manager and customer service to determine where the breakdown occurred that they didn't respond in a timely manner to resolve the issue.

My only suggestion would be to try to edit the letter down a bit, as it is a bit long and a bit hard to read through the whole thing.

I hope you do get a response from Pizza Hut, and I hope you to to the cops on this one as well. Please let us know how it all turns out.