If you approach the restriction head-on they could argue no advance warnings are needed because you can turn off right. - Incandescent
True, but the OP approached Grove Road from De Crespigny Road, where there are no advance warning 'No right turn' sign(s). But photo PCN9 is pretty damning

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@Miflock By my calculation, you must make a representation online before midnight tonight to ensure that re-offer the discount is re-offered when they reject. Hence the suggestion in my earlier post:
If you are certain there is no advanced 'no right-turn' sign in de Crespigny Road you could make a simple challenge of inadequate signage to each PCN within its discount period to preserve discount.
What is the date of the other PCN?
We still don't know the date of the other PCN.
Make a simple rep. (separately for each PCN) along the lines of
Dear Sirs,
PCN JK12345678
I wish to make representation against the above PCN on the grounds of inadequate signage, on the grounds that there is no advance warning in De Crespigny Road of the oncoming no right turn restriction.
Yours faithfully....Make sure you keep a copy of any acknowledgemen/automated receipt.
You will then have bought yourself more time to see if there are realistic grounds of appeal.