The advice about what you want out of this is sound. In fact all of the advice so far has been really good. From my own experience receiving and taking actions on complaints like this I can offer the following additional advice:

• Most public companies take corporate/executive escalations very seriously
• The more effort you put into the complaint (mail > email > phone call), the more seriously you will be taken
• provide dates, times, and names
• Stick to the facts and leave out emotion or opinion as much as possible
• Kind of opposite of the effort advice above, but keep the whole thing brief. Rambling paragraphs are easy for the eye to skip. Some of the most powerful complaints I’ve seen are only a few sentences long.

Good luck!