Read it, then send it. Nothing leaves until you say so.
you said leads come in fine but almost none of them qualify. that usually means the qualifier is asking what someone does instead of what they've already tried. i went through the okafor funnel this morning and there's a gap between the opt-in and the call booking where you lose the people who were closest to buying. what does your current qualifier ask them before they hit the calendar?
you mentioned paid meta is getting more expensive per booked call. that's usually a symptom rather than the problem itself. the thing i'd look at first is what happens between the ad click and the booking, because a rising cost per call often means the page is doing less of the selling than it used to. how many of the calls you book right now actually show up?
one thing worth checking on your side: you said fulfilment is capped and you can't take more clients. that changes what's worth fixing first, because more lead flow would make the problem worse rather than better. is the cap a people problem or a process one?