I had a private number plate starting OO03 and cameras were misreading the VRN as a 03 number plate.this was admitted by the TFL.
So they weren't misreading the plate. That is a 03 plate. (If they were actually misreading the plate how could they possibly have associated it to you?).
I suspect what you really mean is that the database entry associated with that OO 03 xxx plate showed a non compliant vehicle (which was actually compliant).
There are certain issues (which depending upon your point of view may or may not be TfL fault) with ascertaining compliance and it is an imperfect system.
Factors around this involve whether or not the vehicle was constructed against a specific euro 6 standard (assuming it is diesel) and when.
These issues occur because the only registered information may not be definitive dependant upon the actual date of the vehicles registration and when the plate was transferred (if indeed it was rather than being assigned at first registration).
The NoX figure is what matters (and in certain cases the particulates). These may be recorded dependant upon date of your V5c (there are variants of these).
A redacted copy of your V5c may help, but only in ascertaining whether TfL should have known it was compliant.
There is a process documented on TfL website which they expect people to engage with for challenging a vehicle and updating its records. I assume you didn't engage with it (which could simply be because it is poorly publicised).
It may be the case that TfL haven't been negligent. That depends to an extent on how you responded to the PCNs etc.
