As above, pl post the PCN, both sides.
That the PCN was issued at **** does not mean that it was served then, it had to be printed, signed, placed in an envelope etc. Even less do the PCN's times necessarily align with yours e.g. you could have returned 20 minutes after the PCN was issued.
For me, unless you can evidence the time at which you returned to bolster your plea for mitigation, then you'll* be looking at prospective procedural errors.
*- are you the registered keeper with current DVLA details?