It's deplorable to be made to wait for an appointment.
I recently went to a specialist - my appointment was made in June and I was to be seen at 3:20 pm on a Friday in September; I wasn't seen until almost 6 pm. By the time I was finished with the doctor, the support staff had already left for the day. The doc was supposed to schedule me for a chest x-ray and abdominal ultrasound, and she told me the radiology department would contact me on Monday with my appointment times for the x-ray and ultrasound.
By the following Thursday, I hadn't been contacted with appointment times, so I called the hospital myself and tried to figure out when I was supposed to show up. Turned out there were no requisitions posted in the computer by the doctor. So I had to call the office and leave a message with her nurse and let her know the situation. It took her almost 2 weeks to get back to me, and assure me that the tests had now been ordered and I should be hearing from them within the week to book the appointments. That was 3 weeks ago. So I have to get back on the phone tomorrow and find out what happened with the requisitions again, and see if I can find out when I'm supposed to go for these tests.
Do you want to know what absolutely kills me about this? This institution is where I work. This kind of bungling is a professional embarrassment. Nobody should have to wait three hours to be seen by a physician when they've waited months for their appointment already. You do all the right things - you confirm your appointment, clear your calendar so you can actually go to the appointment, and then they can't even see you at the time you're scheduled. If I showed up 3 hours late to an appointment, they would charge me $75 for being late... because THEIR time is valuable. But can I charge them $75 for the 3 hours I waited or for the 3 hours' worth of parking I had to pay? (yup! I have to pay to park at my place of employment!) or for the wild goose chase I've been on trying to get my follow up done before my next appointment in February? Not on your frikkin' life.
I think I may need to write to the CEO to voice my frustrations. Not that it will do any good; hell, maybe I'll end up having to look for a new job.
As far as your situtation - there's no excuse for being made to wait 90 minutes for a 10:30 am appointment, whether they are "squeezing you in" or not. That's just nuts. Hopefully the next experience will go more smoothly - and I hope you have a receipt for the payment you made today that you're applying to the next appointment.