Calling RCI customer service only gets you to the call takers, not the real service representatives. This is why I suggest you put it all in writting, including the travel agency's refusal to address your situation and the other documentation and send it in (my suggestion is registered mail) to RCI Customer Service. The call takers are trained to tell you that if you booked through a TA, you must call them. At least this way you get your problem to the actual service reps and you have a better chance of getting satisfaction.
My suggestion with the travel agency is to just report them to the Better Business Bureau. You probably won't get much satisfaction from them, but atleast you've reported them. The amount of money probably isn't enough for any legal action.