To answer your, "What can we do" question, we can say no.
You can research the newest protocols and tell your vet that you will not be doing it the old way anymore. You are your pup's advocate.
Every three years (after one year booster) isn't a bad schedule for DHPP. It's a compromise. With the exception of rabies, Ellie will not be vaccinated anymore for anything unless I start to get really nervous about it.
She is eight. I am not recommending this, but it just goes to show that many schedules are available to choose from.