When people don’t respond to your calls, faxes or emails they may not realize the significance of what you need. They might forget or misplaces things. They could be overworked and hampered by others’ delayed responses.
(For internal employees): State on top of the memo in bold writing- "In order to reserve a spot for this session, you must return this form to me by 10/21 at 2 PM. If you do not respond, we will assume you will not be coming. You will not be able to attend if you do not RSVP." Let them know what the consequences are so you do not continually have to seek people out to get their responses.
(For customers): Make sure you are making it easy for them. If you need a response, print it in bold up front. Don’t bury it in the memo. If there is a consequence, state that in a friendly manner- "In order to best serve you we need to get the following from you by _____ (Put a specific date here. If you say "within the week" they will not have a deadline in mind and will forget.) If we do not receive it by that date, we will be unable to process your paperwork, which would mean action on your request will be delayed. Please call if there is any problem getting this information to us by the above date. We would love to be of assistance."