Messaging and call-to-action. Add a link or so, to see if they are clicking on it or not. It will tell you if the content is engaging enough or not.
If they are clicking and still not booking, then the CTA can be weak. Try adding a calendly link. Give them clear instructions to take action. For example, I have tried 'If you are interested, just reply with 'yes'. And when they used to reply with yes, I used to send a call invite for the exact same time for next day. Was able to increase calls drastically.
All the best.