therapy agencys always have on call people and your therapist has probably made sure someone was picking up his caseload while hes not available. So you could call the agency again this time asking who the on call person is and who is picking up your therapists caseload and possibly make an appointment with one of those people.
You might want to also make plans for setting up your own personal back up person with your therapist when he is back to seeing clients. That way if he should not be available in the future you will know who to call and see while your therapist is out on vacations or personal leaves from the agency.
I always set up a back up person because I hate having to go through the on call and them not being familiar with me or what my therapist and I are working on, and also for those times when my therapists are on vacation or out on leave or jus plain not taking calls that day or night because they want and need some down time. Or my therapist is teaching a class at the moment I need her.. basically for any number of reasons having a back up therapist is good. By having a back up I know that I am never left hanging without help if I ever need it day or night, holiday or whatever.
Setting up a back up person is easy to do. You, your therapist or both choose a therapist (usually within the agency where you already recieve therapy), I chose the first back up with this therapy agency and LL (my present therapist chose my present "back up" therapist. once you have one in mind, ask that person if they would be willing to be your back up person should your therapist be unavailable. if that person says yes sign release forms so that the back up has access to your file and information about you so that when the time comes and your therapist is unavailable the back up person is familiar with your file and your treatment plans. and then no matter why your therapist is unavailable you will always know who to call and who will be helping you.