You may have tried this already, but see if you can make your message more specific. It can sound counter-intuitive because it seems like you may be narrowing your scope, but specificity is what gets people's attention and turns them into buyers.
For example, some massage therapy centers may focus on "relaxation" - which sounds good - we all want to experience more relaxation, right? But it is also pretty generic. What about focusing your message on some specific audiences and their problems. (I'm making up examples, of course, you're the expert at what massage therapy can do):
- Research suggests that regular exercise reduces migraines (I'm assuming this is true, you might reference a specific source/study)
- reduces post-surgery pain and improves circulation
- improves recovery after exercise (advertise in conjunction with a local marathon, triathalon, etc.)
- reduces insomnia and improves sleep
People won't necessarily pay for "reduced stress," but they will pay for having a few less migraines or being able to get a restful night sleep. Having satisfied customers mention specific benefits related to their needs.
You could do this with specific copy in your FB ads, information on your website, email, direct mail, visits to specific locations/offices.