That makes things nice and easy, draft representation:
Dear London Borough of Bexley,
I challenge liability for PCN XL96093869 because I don't own and have never owned the vehicle concerned. The penalty charge notice is in any event out of time, and must therefore be cancelled.
Yours faithfully,
Send this online and make sure to keep a screenshot of the confirmation screen.
The council will likely reject but it's an easy case to argue at the tribunal.
Send this on 13th to buy the most amount of time possible:
Dear London Borough of Bexley,
I dispute liability for PCN XL96093869 because I have never owned the vehicle concerned.
Yours faithfully