"Sent invitation for scan after scheduled date"

My wife is 18 weeks pregnant and got her obstetrics op appointment on 7th November 15, but on the day of appointment just 2 hours before they called to say that she cannot be seen on that day coz they are out of time. We rang the dept. after few days to know what's going on, and told that her appointment is booked on 26th November 15, but we insist it's too late as she needs to have her scan done as well. We were transferred to the scan department, she told us that it's not late and scan will be arranged after that. But on 12th November15, we received 2 letters, 1 for 26th nov. appointment and the other is for scan scheduled 10th of November15 which is already passed.

I don't understand why St George's hospital sent letter for appointment after the scan date. Is it just for formalities? This time no body pics the phone if you call them.

Question is what other better services we can expect from them !!