Contact by e-mail?

Hi,
I was just wondering is it acceptible to contact an escort by email seeking additional info before making contact by phone? i have asked a couple for additional info as tactfully as I can but got no response!
Is this common not to hear back and is it taboo to discuss extra charges, limits to the amount of time's you cum? obviously I don't state it as bluntly as that in the email or should I have?
The reason I pick email initially is to avoid any language problems.
Any advice for this newbie gladly taken :)