"Confidential information shared"

So over the past couple of months I've been attending Midland saint John of God Hospital for my antenatal appointments, as I'm currently heavily pregnant. During my time making appointments and cancelling appointments there has been a lot of confusion.

So I am a twin and have a twin brother. We share the same last name and date of birth, and what keeps happening is hospital admin staff will ask for my last name and date of birth, but instead of booking under my name they will book under his. This has meant I've lost information, as it's not being sent to me directly, but actually to him (appointments, check ups etc.). He has become quite stressed about this as my information is being submitted under his name and has become worried about his own medical records as am I. I'm afraid that half my information is under his name and half is under mine.

A couple of times I've needed to cancel my appointment, but have been told I never had one only to find out they have booked it under my brother's name again. On one occasion they called him to confirm one of 'his' bookings which he obviously knew nothing about causing him to stress about his own family, at this point hospital staff disclosed all of my personal details to him which is highly unprofessional as he is not listed anywhere as a next of kin

I need this miscommunication to stop as it has been causing a lot of stress on both sides.