You are running ahead of yourself: at the moment you need to get into a postion where you are able to challenge the original PCN.
The process is explained here
https://www.ftla.uk/announcements/charge-certificate-cases-under-the-traffic-management-act-2004-no-original-pcn/
Follow the process as explained there. Keep within the timescale and the PCN will be re-issued and then you can make reps.
Miss the deadlines and it gets very messy.
Reading's letter is out-of-process, but without it you would not have known about the PCN.
Needless to say, they don't tell you about the reset process, but demand payment immediately.
Any reason why your mail (PCN & charge cert.) may have gone astray?
Thanks John, I just followed the steps in the link you provided,
TEC said they haven't got my PCN in the system atm and advise me could call the council to discuss.
Should I reach the council or just keep calling again in every 7 days until its in their system. Cheers.
My address is a terraced house near university area with 3 individual flats in it,
we haven't got any postbox but letter plates on the front door.
We shared the front door & hallway, sometimes even the front was not knocked,
anybody could easily just walk in and grab any letters or parcel,
even the front door knocked, landlord & properties agents got spare keys to access.
I guess thats the reasons.