For bills from Rady Children's Hospital-San Diego: Contact us at 858-966-4912 or pfscustomerservices@rchsd.org. If this is a bill from a physician for a specialty service, your guarantor number will begin with "S." For bills from Rady Children's Specialists of San Diego: Contact us at 858-309-6290, 858-966-5420 or mpfcustomerservice ....