Please review your dates, you mean 2024 not 2023, yes?
received on Aug 7, a charge certificate saying that the notice to owner received on Jul 3 was ignored. It can possibly have been wrongly sent to old address - I changed V5c address in May so not a problem from my side.
ALL notices sent by post MUST use the address of the registered keeper on the date of the contravention UNLESS the authority are informed by the keeper otherwise. They wrote to you to reject your initial reps but at which address, old or new?
If your old and when you moved you did not tell authority and did not put in place mail redirection with RM then this might explain the missing NTO.
But it can't explain how you then received the CC.
OP, to which addresses were the initial rejection and CC sent?
This is very much 'a problem from your side' I'm afraid, but perhaps not irrecoverable.