A Healing Touch

I have 1 treatment room so the facility to offer more than 1 service should be possible, at the moment I can only offer 1 service. As example if I want to offer a Reiki treatment and a massage treatment in my services I can't because even if one client books the Reiki service another client could still book the massage on the same time slot. In short, once a slot is taken whatever the service is, it should be completely blocked and no other service should be able to be booked on that slot. Its really bad and I'm looking at another booking system if this can not be rectified, its unworkable for me. Hope you can help.
Thanks