Some things about your post do not make sense. You say you were re-routed on Continental from Mexico City. Continental does not serve MEX to LAX non-stop. If you had a service interruption on Continental, it would have been in Houston or Newark, which is where they fly from out of MEX. Here is the link to their route map for verification.
http://www.continental.com/CMS/Conti...rld_201012.pdf
Therefore, what airline did you fly on between MEX and LAX? If there was a delay on that airline due to mechanical reasons, why did you not go to the airline which actually caused the delay? Continental is not responsible for issuing hotel vouchers to customers of other airlines, even if they are connecting to Continental. This is in the contract of carriage, but since you are a frequent flier I'm sure you know that.
Also, where was your final destination. From LAX, Continental serves Newark, Cleveland, Houston, and Hawaii. With the exception of Hawaii, you would not have been routed via LAX to get to any of Continental's city. If you stated your case to customer service at Continental as ineffectively as you've done here, I would not respond to your letter either.