I understand from previous communications with Innisfree they meet most flights from Dublin. They have offered a EUR12.50 per person fare to Orihuela Costa in past if you arrive on one of those flights. Not sure if they still do.
If you are arriving from somewhere else they will put on a car or a van for your group. Prices per car from eur40 up.
If you happen to arrivie about 3 or more hours before an incoming flight from Dublin and are happy to wait they may be willing to include you on one of the Dublin transfers.
I suggest not using email and reserving by phone. Often it requires a bit of two way communication to fully understand your options.
Strange thing is you seem unable to prepay so yes they can cancel at short notice. They do however still get upset If a passenger cancels a reservation at short notice !