international student, PCN at uni, appeal rejected

Hello everyone.
It is my first post and would be appreciate if you could be patience about my questions if it is duplicated. I carefully examined many posts regarding PCN on this forum but still very confused (may be due to language problem) so really need your kind help.

[Background] PCN at the uni on 7 Feb 2018
1. I am an international PhD student, living with two children.
2. Me and my son had dentist appointments at 11:25 AM and 11:50 AM. I remember our filling treatments were finished at about 12:15 PM.
3. I dropped my son at his primary school again and rushed to my university and parked my car in the parking space of the university (only 60 mins short stay free, no pay and display available) as I didn't want to miss the lecture, which was supposed to start from 12:30 PM (to 1:30 PM for 1 hour). I don't exactly remember exactly when I arrived the parking area but I guess it would be between 12:28-1:30 PM.
4. I was fully aware of that I am eligible to park there for 60 mins and no doubt that I would move the car before the allowance.
5. My session was supposed to last from 12:30 PM to 1:30 PM. However, when I arrived in front of lecture room, the instructors said the room was double booked accidentally so there was another lecture was going on with other people. Therefore we (students and 2 instructors) all together waited for 30 mins in front of the lecture room.
6. The session started delayed - without previous notice- from 1:00 PM and finished at about 2:00 PM, that means eventually I had to park my car for 90 mins (12:30 - 2:00 PM). I have two contact points that verify this situation.
7. When I got back to my car about 2:00 PM (it only takes 1-2 mins from the lecture room to the parking space), I found a yellow windscreen PCN from the university. (£80, discount £30 within 14 days)

[Their Evidence]
The university uploaded 9 pictures of my car, which were taken at 13:55 and 13:56 PM. There was no picture before that time.
However, on their windowscreen PCN they indicated my car was parked there from 12:27 PM so that's why they issued PCN at 13:56 PM. I am not sure whether they really took picture at 12:27 PM or not but they didn't upload the arrival picture on their evidence page. All the pictures they uploaded were took 13:55 and 13:56 PM

[What I did up to now] made a appeal to the university on 8 Feb 2018
There PCN indicates that I can appeal against the PCN via their online site.
So I explained all the things, which I mentioned above, including my full name, my address, the instructors' name and email address, and the dentist telephone number and address.
What a silly thing I did!!!!!!

[What I got after the appeal] got a reply on 9 Feb 2018
The university sent me a reply letter to my address, just 1 day after I submit my appeal online, with a reject as follows. (What a super fast response although I wrote a lot!)

"That you for your recent correspondence regarding the above notice number. I have considered the case carefully and have decided to reject your appeal on the following grounds;
The above Parking Charge notice was issued to your vehicle as the parking attendant has recorded that your vehicle was parked for longer that 60 minutes in a 60 minutes short stay bay. It is responsibility of the motorist to ensure they are aware of the restrictions within the car park and ensure they park in accordance to these restrictions.
University of OOO care parks are private care parks and by entering you agree to the terms and conditions and therefore enter into a contract. The motorist was in breach of the clearly signposted terms and conditions when the vehicle was parked and is therefore liable for payment of the above Parking Charge Notice.
I am confident that all signage and the PCN are compliant with all industry standards and to the IPC's code of practice to which we subscribe.
.........................
If you believe this decision is incorrect, you are entitled to appeal to the Independent Appeals Service (IAS). In order to appeal the IAS will need your parking charge number, your vehicle registration and the date the charge was originally issued. Appeals must be submitted to the IAS within 21 days of the date of this latter. For further information please visit theias.org."

I would sincerely appreciate if you could advise me what I can do from now on...
I am feeling like I was too foolish, innocent, kind to let them know all the personal information.. (I simply thought the university would understand my situation and cancel PCN straighforwardly.)
I also think I am too vulnerable to win this debate as I am an international student and I am not fully aware of UK's laws etc. so very desperate....

Thank you very much for taking time to read this post.