Exactly what I was saying: in big practices, the front office person is a receptionist. You don't ask them for advice, usually they schedule appointments.
In our practice, its small with two vets, so unless the vets wife is in the office doing scheduling, we, the vet techs do it all. But we are not vets, so don't give medical advice, we get the vets on the phone or have them return the call as quickly as possible if we can't relay their message to the phone caller.
I don't beleive the vet failed this person, I beleive the person failed to even talk to a vet during the day, just asked the receptionist what to do. It does sound like the on call vet did not understand the person WANTED a vet to come out after reading more and more replies from the OP, it sounded like they called, told them the mare foaled and seemed okay and didn't actually ASK the vet to come out. I don't beleive it was the on call vets fault, I don't beleive the caller made it clear that the mare had a previous foaling issue and didn't explain how concerned they were. I can't beleive any vet would refuse to come out if a person "begged" the vet to come out. If that is true, then yes the on call vet failed and the owner of the practice needs to be notified that the vet is not doing his/her job and refused to come out on an emergency.. but, the OP can't hold the receptionist responsible for not telling a vet that a call was immediately necessary if the OP did not TELL them it was necessary.